In order for the GUIDE button to function properly, the TV Provider must be set up in Apple settings. Sign in to your Provider by going to Apple Settings -> Users and Accounts -> Apple TV Accounts: TV Provider -> Sign in to TV Provider.
In order for the GUIDE button to function properly, the TV Provider must be set up in Apple settings. Sign in to your Provider by going to Apple Settings -> Users and Accounts -> Apple TV Accounts: TV Provider -> Sign in to TV Provider.