Poorly designed app that can cost you more than it’s worth
The app automatically transferred the amount from an Apple Gift card to the Apple account balance, which you cannot use in the physical Apple Store. There was no confirmation required for this action: it was enough for me to tap the Gift card code (in an attempt to copy it) for the transfer to take place. We also had a very poor experience with C&A gift cards. My advice: just delete your account and forget you ever heard of this app.