Seeing that you already have your invitation to come to Maastricht, you probably as well received the information package before. In the FAQ you can see that you do not need to prepare yourself (too much).
Don't worry and be yourself. Ofcourse a bit of knowledge of aviation/ATS can help a bit. But all the other tests you cannot really prepare yourself that much.
So don't worry and be happy
Good luck
By the way don't expect to be in a 5-star Hotel
Maastricht can be a nice city to visit specially at night (just watch it if you still have some tests the day after)