This Mac can’t connect to iCloud because of a problem with [email]

You might want to try turning it on. That was my point, actually. Apple is moving toward requiring Two-Factor, so it is possible that the problem lies therein:

Two-factor authentication for Apple ID - Apple Support

If you have any apps (other than iCloud apps) that are using iCloud, then it is likely that that is the issue. If your Apple ID was set up before iOS 10 or macOS Sierra, then you can turn it off again.

Best,

GB

Try setting up another admin user account to see if the same problem continues. If Back-to-My Mac is selected in System Preferences, the Guest account will not work. The intent is to see if it is specific to one account or a system wide problem. This account can be deleted later. Please post if this worked or not.

Isolating an issue by using another user account

If the problem is still there, try booting into the Safe Mode using your normal account. Disconnect all peripherals except those needed for the test. Shut down the computer and then power it back up after waiting 10 seconds. Immediately after hearing the startup chime, hold down the shift key and continue to hold it until the gray Apple icon and a progress bar appear. The boot up is significantly slower than normal. This will reset some caches, forces a directory check, and disables all startup and login items, among other things. When you reboot normally, the initial reboot may be slower than normal. If the system operates normally, there may be 3rd party applications which are causing a problem. Try deleting/disabling the third party applications after a restart by using the application un-installer or by using the developer’s uninstall instructions. For each disable/delete, you will need to restart if you don't do them all at once. Please post if this worked or not.

Safe Mode - About

Safe Mode Startup – El Capitan. also Sierra

If it works in the Safe Mode, try running this program when booted normally and then copy and paste the output in a reply. The program was created by Etresoft, a frequent contributor. Please use copy and paste as screen shots can be hard to read. Click “Share Report” button in the toolbar, select “Copy to Clipboard” and then paste into a reply. This will show what is running on your computer. No personal information is shown. You can run the report for free at least once, but if you run it several times, at some point it will ask you to pay a license fee.

Etrecheck – System Information

Do you have Two-Factor Authentication turned on? I had to sign into Messages on my iPad 1, so had to turn 2FA off on my Apple account to do that. When I did, that same message popped up on my Mac screen. Once I turned it back on it went away:

Two-factor authentication for Apple ID - Apple Support

Best

GB

The reference to EtreCheck is to have you download, install, and run this app to create a report so that we can see if there is something amiss with your Mac that we can identify and help you resolve.

A bit more "step-by-step" follows:

• You can download EtreCheck from here.
• Start EtreCheck from a normal user account. Optionally, you can run it from a user account with Administrator privileges.
• Select a problem from the drop-down menu to enable the "Start EtreCheck" button. Optionally, you can add comments on what issues your Mac is experiencing, especially to aide others with similar Mac issues.
• Click on Start EtreCheck
• Allow the program to run to completion.
• When done, select Report from the left-side window to display it.
• Select the "Share Report" icon.

  Select Copy Report

• Paste the report to your reply post.

Mounted Volumes:

disk1s1 - Macintosh HD 121.12 GB (24.55 GB free)

APFS

Mount point: /

Encrypted

disk1s4 - VM [APFS VM] 121.12 GB (24.55 GB free)

APFS

Mount point: /private/var/vm

Your MBA does not have a lot of free hard drive space. Unfortunately, this is typical as these notebooks do not have a lot to start with. You may want to consider removing any apps that you are not using or use very often.

32-bit Applications:

23 32-bit apps

Not an immediate issue, but fairly soon a future macOS upgrade will no longer allow 32-bit apps to run. I believe this is coming this summer so just be aware. You can find out which of your apps are 32-bit ones by going to: Hold down the option key, and then, click on the Apple icon on the macOS menubar > Select System Information > Software > Applications. Depending on how many apps are on your MBA, it will take a few seconds/minutes for a list of all the apps are displayed. Look under the 64-bit column. If "No" is listed, then this app is a 32-bit one. If you use this app, you will want to get with the developer to see if they have a 64-bit version available. Those that you don't use often, I would suggest that you uninstall them.

Software Installs (past 30 days):

Name	Version	Install Date
WhatsApp	0.2.9230	2018-05-14
Todoist	7.0.13	2018-05-30
iTunes	12.7.5	2018-05-30
Adobe Flash Player	29.0.0.171	2018-05-30
TeamViewer	13.1.4170	2018-05-30
PS4 Remote Play	2.6.0	2018-06-05
Gatekeeper Configuration Data	140	2018-06-05
App Cleaner & Uninstaller	5.0	2018-06-09
Spark	2.0.4	2018-06-09

I would recommend that you uninstall App Cleaner & Uninstaller. Cleaner apps tend to cause more problems than they solve

Can you successfully log into Manage your Apple ID with the ID that you are trying to use with your Mac? If so, have you tried logging out of your ID, and then, back in?

As a test, you also might try quitting TeamViewer.