As for whether it is free, I am not sure. There are full refunds and partial refunds, which need to be carefully read when signing the agreement.
Generally speaking, they will sign an agreement class for you when they are sure that you are ok. If they are not at ease, they will advise you to sign up for the agreement class and not refund some money. Only if the organization is confident in your interview will it give you the kind that can't be signed and can only be returned in full.
So, your purpose is to get into the civil service, not just focus on money. Being admitted is the most important thing! Come on!