Logging in to Apple TV+ without an Apple device.

I'm trying to login to Apple TV thru my Xfinity box. I've subscribed to Apple TV & have an Apple ID already for my music. My options are "sign on thru a mobile device" or "create a new apple id". When I select the former mobile device option it just spins. I can login thru my phone but doing so doesn't change anything on my TV(it's still just a spinning wheel).