Wi-Fo on American Airlines

The other day I was on an American Airlines flight and was unable to find out how to connect to the free T-Mobile free Wi-Fi service. Does anyone have any advice as to why it didn't show up? I did see the Viasat app but not T-Mobile.

I followed the 4 steps moted in the “How it Works” section -- “Look for the T-Mobile logo on the page and enter your phone number to verify eligibility and start using in-flight connection.” not there and I am a Magenta  plan owner.