STARZ subscription (through appletv)

I recently decided to subscribe to STARZ through my AppleTV account (apple has issued me the invoice monthly). When I go to the app it doesn’t recognize my subscription at all and asks me to log in or create an account for a 3 month subscription. There is also a tiny icon at the bottom that says “restore iTunes purchase”. I’ve tried all of these to no avail. The only way I’ve been able to watch movies is to browse STARZ and close out of the app then tell Siri to find the movie/show and when I select it, it’ll say it’s available on STARZ and I can play it there. But on occasion (like tonight) I wanted to play Diamonds are Forever and it kept giving me the log in screen and would not play the movie. So what am I doing wrong??