AS i und erstand it you need 3things to install a game:
1. Wud files
Your encrypted game
2.Titlekey
The key to decrypt the game(Like a password)
3.Ticket
It tells the wiiu you own the game. Can be faked(so that you can only play in haxchi mode), boght from the eshop or riped from a gamedisc (that makes it Luke a legit CIA in the 3ds)