I need to sign into iTunes Store to watch TV???

I just signed up for AppleTV+ and am watching "The Morning Show". About 10 minutes into the show, it stops and says "To watch this content, sign in to the iTunes Store". Can someone tell me why that is?

I'm using a ROKU streaming stick to watch on a VIZIO tv. Is that the problem?

(There hasn't been any problem when watching Netflix.)

I went to my apps on my computer, found iTunes Store, but don't see where I need to sign in.

Thanks for any help.