Apps on Apple TV and cable subscription
Do you have to have say, CNN on your cable subscription in order to watch CNN Go on Apple TV?
Apple TV, iOS 10.0.2
Yes.
http://edition.cnn.com/specials/about-live-tv
Why do I need to sign in with my TV service provider information?
Your TV subscription that includes CNN is your key to watching CNN TV online. When you sign in through your TV service provider, you confirm your CNN TV subscription.