Went to the Audi Cup tournament we played in back in August 2017. Son already had a card from going to watch Bayern in a bundesliga game. You just "load" the card with credit, paying at a kiosk, and then use it at any off the beer and food areas. (Non-alcoholic beer by the way!). Cracking ground, dead envious of those going. Tried to purchase tickets with our qualifying season tickets but, like many others, sold out.