Not able to use UVerse app on iPhone or iPad anymore

I am no longer able to use the uVerse app on my iPad or iPhone 13 Pro Max.  I used to use a specific login provided by AT&T which was not my AT&T email address.  That login no longer works so I called the Loyalty Program. They said that I need to use my AT&T email address but when trying to log in using my AT&T email address and password, I receive a message stating 'That isn't the ID set uo for this service. Try signing in with another ID. Care Code: 205.4'

The AT&T rep said that I need to use my AT& T email address to log into the UVerse app but I am not able to do so.  Anyone else have this problem?