This app was mentioned in 6 comments, with an average of 0.17 upvotes
The app is a War Thunder Mobile Assistant, not a mobile port of the game, which Gaijin have repeatedly said would be impossible and they have zero interest in making.
The assistant app is rather outdated, mostly you could use it to check your own stats and vehicle stat cards. There was also a virtual poker game in the app, but you won't find anybody playing it.
it does have an mobile app https://play.google.com/store/apps/details?id=com.gaijinent.WarThunderCompanion&hl=en
The purchase was not authorized, this is the exact case that page describes, OP is a minor using their parents' money. The parents did not authorize the purchase.
As for gambling: https://play.google.com/store/apps/details?id=com.gaijinent.WarThunderCompanion
https://puu.sh/t3FTB/54d1096b96.png
https://www.reddit.com/r/Warthunder/comments/5kmnog/psa_trophy_boxes_for_the_winter_event_not/
As for the odds, apparently this only affects companies registered in Australia and not offshore companies offering services to Aussies, so you get that one.