I just hooked up my Apple TV. How do I choose Spectrum as my TV provider?

What is your model Apple TV? Identify your Apple TV model - Apple Support

Spectrum TV requires a current model Apple TV, not 3rd generation or earlier.

The TV provider setting requires a current model Apple TV, not 3rd generation or earlier.

Spectrum TV uses the Spectrum TV app, and the TV provider setting is optional for select other apps.

During the initial setup of a new/blank/reset Apple TV box, you would be asked to select a TV provider, if applicable.

For already configured Apple TV boxes, you may find the TV provider setting in Settings﹥Users and Accounts﹥. One TV provider can be selected at a time, so any previous selection will need to be forgotten.

Use your pay TV or cable provider with Apple TV - Apple Support

TV providers that let you sign in on your iPhone, iPad, or Apple TV - Apple Support

Apps that let you sign in with your TV provider on your iPhone, iPad, or Apple TV - Apple Support

If you have Spectrum TV and Spectrum internet, then it should detect the TV provider automatically (Zero Sign-on).

The TV provider setting does one thing: sign in on select apps that support this automation, so you don’t have to do it manually for multiple apps. It doesn’t bring you anything else. Not sure if you would use those other supported apps (ABC, NBC, etc.), as those channels would also be available within the Spectrum TV app.