Starz app says "Not Authorized" when trying to activate

I have Starz. It's part of my AT&T UVerse plan....I had to fill in some category fields incorrectly, since this is a Direct TV forum....but this is where i went when I googled my problem (I can't switch to Direct TV - too many trees for a dish they tell us).

Why does the Starz app tell me I'm not authorized to activate (or even watch) Starz on the app? I can watch it on my TVs.

I saw the same question elsewhere, dated a YEAR ago. How can this still be an issue?

(I am trying to activate STARZ using AT&T UVerse as provider and my AT&T login.)

Thanks in advance - I'll call ATT if I have to, but want to avoid that headache if possible.