Vika_gusakova wrote (Google translated):
Setting up Apple ID
Hello, I want to link your Apple ID to my Apple TV. But I'm getting a message that I can't sign in to my account because iCloud isn't set up for this Apple ID account.
Can you help me? I have iCloud set up, but I don't understand why Apple ID doesn't see it.
If you have a legacy model Apple TV box (A1378, A1427, or A1469, i.e. from before 2015), then unfortunately those models do not support iCloud services anymore. At this time, users would need model A1625 or newer to use iCloud services on there.
You may keep using such an older model for the remaining functionality, but not iCould services.
The error message is a bit confusing, like there would be an issue with the account, but instead the issue is with the system software on these older models.
Please note that iCloud services [ru] have no direct relation to an Apple Account whose email ends with @icloud.com. These are separate features.
Also see: discussions.apple.com/thread/255664587
Identify your Apple TV model - Apple Support
Find your Apple TV model number - Apple Support