Apple TV is designed for entertainment, not data entry. Ask people to authenticate only in exchange for value, such as personalizing the experience, accessing additional features, purchasing content, or synchronizing data.
Prefer letting people use another device to sign up or authenticate. Your app can send a code to the viewer's other device for authentication.
Delay sign-in as long as possible. People often abandon apps when they are forced to sign in before doing anything useful. Give them a chance to fall in love with your app before making a commitment to it. For example, in a media streaming app, let people explore your content and discover what you have to offer before signing in to play something.
Explain the benefits of authentication and how to sign up for your service. If your app requires authentication, display a brief, friendly explanation on the login screen that describes the reasons for the requirement and its benefits. Also, remember that not everyone using your app has an account from the start. Make sure you explain how to get one, or help people use another device to sign up.
Minimize data entry. Most people interact with Apple TV using a remote, not a keyboard, so don't ask for more than the minimum amount of information necessary. If you need to gather more information, tell people to visit a website from another device. When asking for an email address, show the email keyboard screen, which includes a list of recently entered addresses.
Keep multiple profile support intuitive. Because Apple TV is a communal device, your app won’t always know who’s holding the remote. Default to the most recently used profile at launch, but clearly identify who's logged in and make it easy to switch to a different account.