How to add a new (to me) iMac in my Devices

OK, so are you signed in to iCloud on the Mac with the Apple ID in question? If not, then sign that in. If so, then try signing out then back in. Once you sign into iCloud on a Mac running Yosemite or later, it should show up automatically:

Add a device to the list

After you sign in on a device with your Apple ID, that device appears in the list. Here's where you need to sign in:

• For iOS 9 and later, sign in to iCloud, iMessage, FaceTime, the iTunes and App Store, or Game Center on the device. You can also see your paired Apple Watch.
• For iOS 8 sign in to iCloud or the iTunes and App Store on the device. You can also see your paired Apple Watch.
• For OS X Yosemite and later or Windows 10 and later, sign in to iCloud on the device.
• For tvOS 7 and later, sign in to the iTunes and App Store on the device.
• If any of your devices are using earlier versions of iOS, OS X, or tvOS, you won’t see them in your device list.

Cheers,

GB

Try here: Your Support Profile for Registered Purchases. On the other hand, if you need to authorize it, then you need to de-authorize your old computer if you no longer have it.

Authorization

iTunes Store - Authorize or deauthorize your Mac or PC.

In iTunes you use the Authorize This Computer or De-authorize This Computer option under the Store menu in iTunes' menubar. For Windows use the ALT-S keys to access it. Or turn on Windows 7 and 8 iTunes menus: iTunes- Turning on iTunes menus in Windows 8 and 7.

Deauthorization

You can de-authorize individual computers, but only by using those computers. Your other option is to "de-authorize all" from your iTunes account.

1. Open iTunes on a computer
2. From the Store menu, select "View my Account..."
3. Sign in with your Apple ID and password.
4. Under "Computer Authorizations" select "De-authorize All".
5. Authorize each computer you still have, as you may require.

You may only do this once per year.

After you "de-authorize all" your authorized computers, you may re-authorize each one as required.

If you have de-authorized all computers and need to do it again, but your year has not elapsed, then contact: Apple - Support - iTunes - Contact Us.

For more information on authorization and de-authorization: iTunes Store- Authorize or deauthorize your Mac or PC.

First thing you need to make sure of is that your friend has

removed all remnants of his ownership from the Apple system

by following:

What to do before you sell or give away your Mac - Apple Support

The prime thing is the last, he or she needed to completely wipe the machine

and re-install the original OS and leave it in an "unused state". When you received

it, when first powering up, you should have had a welcome screen.

Unless all of the above steps in the above link were done, you will not be

able to associate that machine to you.

Delivering a Mac in any condition other than the state it would be in after

following the link above would be violating many EULAs of Apple.

It may be a partial reason, depending on the two-factor setup. My iPhone (5c) had

a notice message suggesting to update to that factor security. The iPad Mini (1.1)

with wi-fi works well enough with sharing text via messages, and facetime when

its near the iPhone and while out of range of my wi-fi, can use cellular to do that.

But my most recent mac mini i7 quad (Late 2012) still runs Mavericks 10.9(.5) as

shipped, and I get the impression it may prefer at least El Capitan 10.11.6 in order

to facilitate the other features that may be shared, and a two-factor security.

The two-factor authentication and two-factor verification can be better understood

if you read some articles; there probably is a good one in Apple support. I see a few

from other sources online, some are reputable. ~ Most probably bookmarked Apple's

in my older Mac w/ Leopard 10.5.8, a Late 2005 Mac Mini G4 1.5 GHz; & use it often.

I found the support article which covers both different two-factors here:

• Two-factor authentication for Apple ID - Apple Support

//support.apple.com/en-us/HT204915

Or:

macOS Sierra: Use two-factor authentication for security

For links to read more, you could see some relevant ones here:

https://duckduckgo.com/?q=apple+mac+os+two-factor+and+two-+security+mac%3F&t=ffsb&ia=web

As far as the newer iOS devices go, I've already totally wiped (for new owner or trash

bin disposal) my iPad Mini, four times; & almost broke the display with the stylus of

my iPhone because it wouldn't 'touch' after half a dozen times on certain letters...

So in my experience and as time goes on, I really see little actual need to own these.

And I'm at fair distance most of the time from barbaric + radical elements of civilization...

In any event...

Good luck & happy computing! 🙂

I included that as well. Unfortunately, I don't really know what you want to add, and to what would it be an addition. If you did not find an answer in what I already posted, then you haven't formed an intelligible question with adequate detail.

You may, if you've not already tried to add a product to the section

where your Apple ID indicates a device is present, try to login to

your Apple ID from each of the devices. If the previous owner has

cleared their personal information and activation is not blocked.

I've recently gotten two previously owned iOS Devices that run 9.3.5

and 10.x (latest supported versions for their vintage hardware) and

these were able to communicate with each other after I logged in to

each via Apple ID and iCloud. Even the wi-fi only iPad Mini was able

to see and use internet, facetime and imessage via the iPhone.

Because I've yet to update the security in the Mac to use two-factor

the Mac won't let me share content easily with these iOS devices.

So, if there is a list of products (from the Mac point of view) I've not

seen it yet. And the older 'purchases' list of my 15+ years of buying

stuff from Apple, seems no longer as easily found as that once was.

The setup of each item and how, has something to do with how they

are seen by others of your grouped iOS Devices or shared products.

In any event...

Good luck & happy trails! 🙂

The "new" iteration of this page:

https://appleid.apple.com/

will no longer allow you to add anything manually (the old support page disappeared when the new one showed up - a lot of accessory devices which were on my old page also disappeared). A device will automatically show up - I just purchased a new Macbook Air and, although, I had not set up iCloud at all (since I do not use it), but had signed into the app store with my Apple ID, it showed up immediately. I do not know if used devices not purchased from Apple will show up automatically or not. If they do not, there isn't anything you can do since there is no option to add anything.

What list do you mean? I gave you a link for adding it to your registered products. What is this other list?

Your list of Apple Devices where? On your Apple ID page? On your iPhone? On iCloud? Is the Mac running OS X Yosemite or above? If it isn't then it won't display anywhere.

Cheers,

GB