"Sign in to an existing Apple TV with your pay TV or cable provider
You can sign in to Apple TV to access content through your pay TV or cable provider. Just go to Settings > Accounts > TV Provider to sign in. This single sign-on allows you to access apps using your provider, so you don’t have to sign in to every channel's app.
Some providers might automatically sign you in to access their content if your Apple TV is connected to their Internet service.
Your provider might also offer an app in the App Store with extra features like on-demand and live television. You might be prompted to install the app when you sign in, or you might need to download it separately. The app might also be available for your iPhone or iPad.
Single sign-on requires an Apple TV 4K or Apple TV HD."