Hello cristianoCH,
We would like to see how we can help you with using FaceTime on your Apple TV. Do you know if you have a first or second generation Apple TV 4K? If you have a first generation, it will not be capable of using FaceTime with an iPhone camera. For more information visit: Use FaceTime on Apple TV 4K (2nd generation or later) - Apple Support
"Before you begin, make sure your iPhone or iPad is set up to use FaceTime. Open Settings on your iPhone or iPad, tap FaceTime, then turn on FaceTime. Sign in to FaceTime with your Apple ID, if you haven’t already.
- Open the FaceTime app
on Apple TV 4K (2nd generation or later). - On the Continuity Camera screen, do either of the following:
- If you already appear in the list of users: Select your profile, then confirm on your iPhone or iPad.
- If you don’t appear in the list of users: Select Other to reveal a QR code, then open the Camera app on your iPhone or iPad, scan the QR code, then tap Connect to Apple TV and confirm on your iPhone or iPad.
- Note: If you’re signed in to Apple TV, your profile appears in the list of users after initial setup. To add a user, follow the instructions in Set up multiple users on Apple TV.
3.Position your iPhone or iPad near the TV in landscape orientation so that the rear camera (iPhone) or front camera (iPad) faces you and you’re satisfied with the way you appear in the preview on your TV screen. You can also press the Play/Pause button on the Siri Remote to skip this step.
After a short countdown, your iPhone or iPad camera is ready to use with FaceTime on Apple TV.
4.To pause or disconnect your iPhone or iPad’s camera, tap Pause or Disconnect on your iPhone or iPad’s lock screen."
Cheers!