This app is 2.99 + tax but they don't tell you – AR Coloring Book Review

Not only that! After I had put my Apple ID pass It charged my credit card. I downloaded it and there was a black screen with a min the middle the bottom of the app says "tap the screen QR CODE" I tapped until my fingers got sore, nothing t this point I don't know what to do. Need help! Confused.........
Review by pepsi67 on AR Coloring Book.