Generally, a certain fee will be charged. Some institutions will refund you a certain fee if you fail to pass the exam (most institutions promise so, I don't know if they will refund you). As for letting you train first for free, do you think people are stupid? It's just that you were admitted, but if you slip away, you won't be able to take the exam where you are going. You still have to figure out what's inside such an institution, and there will be no pie in the sky!