Why the icloud not available?

Hi Monteza1989,

For help with signing in to iCloud on your Apple TV, test the steps below found in the article here: Sign in to iCloud on all your devices

"Set up iCloud on your Apple TV

1. On your Apple TV, open the Settings app.
2. Choose Users and Accounts, then select your account.
3. If you haven’t signed in with your Apple ID for iCloud, choose iCloud > Sign In, then enter your Apple ID and password.
4. In the iCloud section, choose an app or feature, then turn it on or off."

You can also find helpful information here: Introduction to iCloud - Apple Support

Cheers.