Hmm, seems like there's some kind of confusion between the app and the subscription you have. We might have to have the folks at McAfee take a look at the subscription. Have you reached out to their support to see if they can look into this for you?
Have you contacted support for McAfee for more help? Please let us know. Thanks.
I'm sure you've solved it by now but I think the same thing happened to me.
There are separate apps for McAfee for T-Mobile and McAfee standard security, make sure you download and sign up for the right one. The App Store doesn't want to show the T-Mobile version unless you manually search for it.