Here's a suggestion: make the app free for anonymous use. When you get the login, voting, etc. working correctly have an in-app purchase to enable the logged-in

Here's a suggestion: make the app free for anonymous use. When you get the login, voting, etc. working correctly have an in-app purchase to enable the logged-in features. This way you can build a larger initial base of users and later on upsell them to functionality worth paying for.