iMacmodel A1224 Running Yosemite OS X

Well, if you see a Utility Menu, then try this:

1. Select Disk Utility from the main menu and click on the Continue button.
2. After Disk Utility loads select the volume (this is the indented entry, usually Macintosh HD) from the side list. Click on the Erase button in Disk Utility's toolbar.
3. Set the Format type to Mac OS Extended (Journaled.) Click on the Apply button
4. When the process has completed quit Disk Utility and return to the Utility Menu.
5. Select Install OS X and click on the Continue button. 

It would appear there is a Recovery HD partition on the computer, so you may be able to do the above. However, you may be asked for your Apple ID and password. If it doesn't accept yours, then it wants the Apple ID and password of your friend or the last owner.

You do not select the out-dented drive entry. You want to select the indented entry below it - the volume entry.

APP HDD 500G <=== This is the out-dented or drive entry.

Untitled <=== This is the indented or volume entry. This is the one you should select.

The volume's name is not an issue because it can be left alone or changed later. The one you see above is just an example. Remember you are now doing the following after the Utility Menu appears:

1. Select Disk Utility from the main menu and click on the Continue button.
2. After Disk Utility loads select the volume (this is the indented entry, usually Macintosh HD) from the side list. Click on the Erase button in Disk Utility's toolbar.
3. Set the Format type to Mac OS Extended (Journaled.) Click on the Apply button
4. When the process has completed quit Disk Utility and return to the Utility Menu.
5. Select Install OS X and click on the Continue button. 

I'm at a loss. I don't know why you get that error unless the machine was originally purchased in another country. You would need to call and ask Apple about it. I have never come across such an error. When you reported the error originally, my inference was that you had to wipe the drive first, then install the original version of OS X, but that doesn't seem to be the case. We're back to square one.

If your model is Late-2011 or later:

Internet/Network Recovery of El Capitan or Later on a Clean Disk

     If possible back up your files before proceeding.

1. Restart the computer. Immediately, at or before the chime, hold down the (Command-Option-Shift-R) keys until a globe appears.
2. The Utility Menu will appear in from 5-20 minutes. Be patient.
3. Select Disk Utility and click on the Continue button.
4. When Disk Utility loads select the target drive (out-dented entry w/type and size) from the side list.
5. Click on the Erase button in Disk Utility's toolbar. A panel will drop down.
6. Change disk name, if you prefer.
7. Set the partition scheme to GUID.
8. Set the Format type to APFS (SSDs, only if installing Mojave or Catalina ) or Mac OS Extended, (Journaled.)
9. Click on the Apply button, then click on the Done button when it activates.
10. Quit Disk Utility and return to the Utility Menu.
11. Select Install OS X and click on the Continue button.

To find the complete model information select About This Mac from the Apple menu. You can create a snapshot of the dialog as follows:

How to take a screenshot on your Mac

Capture, Save or Record Screenshots in Mac OS X - Help Desk Geek

OS X Screen Capture Shortcuts

(⌘⬆︎3) Command-Shift-3 Capture the screen to a file

(⌘⬆︎⌃3) Command-Shift-Control-3 Capture the screen to the Clipboard

(⌘⬆︎4) Command-Shift-4 Capture a selection to a file

(⌘⬆︎⌃4) Command-Shift-Control-4 Capture a selection to the Clipboard

(⌘⬆︎5) Command-Shift-5 Invoke new screen grabber

You can then post the image in the forum's message editor.

Should be the same. On a Windows keyboard the Windows key (left side of Space bar) is the Command key on a Mac keyboard. If the keyboard won't work (some do not) then use the one that came with the iMac.

Either one but wired is better. If you must use Wi-Fi, then it should be a fast connection.