The idea of the entrance exam is to test your basic knowledge of maths and physics. Clearly some of the questions are with aviation content. It is not that difficult. After 20 years out of the education system I got 87%, with the wrong answers identified.
Though you send a deposit with your entrance paper answer sheet, they do not cash the cheque until you have passed the exam.
I believe it is the norm to pay up front for most residential courses.
When are you thinking of starting?