I am also having an issue with this. Keep getting an error saying "Sign in with a different account". I tried creating a new account, and it also doesn't work. So no linked to Premium or free accounts. Disappointing, because the collection I got is crashing, and can't read anything about it since it's all locked behind a sign in wall that I can't get past. I just got Premium too, so I guess I'll be canceling that membership since I can't use the features I purchased that membership for.