Apple tv with Apple Tv+ sign in

I'm not an expert but this is what I did when presented with this same issue. Check your Apple TV model to see what generation you have by Settings>General>About and cross-reference your model number to the AppleTV type/generation on this link: https://support.apple.com/en-us/HT200008. Once you have confirmed compatibility, be sure to upgrade to the latest version of tvOS if your AppleTV is not already set for automatic upgrades. Be sure you are logged into your AppleTV using the same Apple ID used to sign up for TV+. Then use this link for info on logging in if you are only presented with "Start Free Trail": https://discussions.apple.com/thread/253298632?login=true

How to watch on your Apple TV

1. Open the Apple TV app  from the home screen.
2. On the Watch Now screen, scroll down to view Apple TV+, Apple TV channels, or featured movies and TV shows, then select an item.
3. Do any of the following:

• • Play the item or open it in a channel: Select Play or Open In. If you haven’t subscribed to the channel, follow the onscreen instructions.
  • Subscribe to Apple TV+: Select the subscription button, then follow the onscreen instructions to confirm your subscription.
  • Subscribe to an Apple TV channel: Select the subscription button, then follow the onscreen instructions.
  • Buy or rent a movie: Select Buy or Rent, then select the option you want and confirm your purchase or rental.
  • Buy a TV show episode or season: Select Buy, then select the option you want and confirm your purchase.

To learn more about the Apple TV app on Apple TV, see the Apple TV User Guide.

Apple TV+ is compatible with Apple TV (3rd generation or later), unfortunately not Apple TV (2nd generation).

All the ways to watch Apple TV+ - Apple Support