How to resolve the "Error 1005, User Canceled / Google Authentication" problem.
This error is caused by the Play Store and can only be resolved by following the instructions from the website linked above.
Be aware please that this has nothing to do with general content purchases like aircraft as those require no authentication. This is specific to a failed GooglePlus authentication relating to a personal account owned by you. We have no visibility on these accounts and are not able to correct the Google error from our end.