If a lender has approved a loan to you they would not normally ask for the payment of an up-front, out-of-pocket fee prior to disbursing the loan proceeds. They can take the fee out of the proceeds at loan closing. I would be very leery of any lender that makes this kind of stipulation to their extension of credit.
First of all, make sure you get everything in writing: the loan approval, the request for the fee, any conditions the lender places on disbursing the proceeds, everything. If they won’t put it in writing, you cannot rely on any of it. Even if they put it in writing, I would recommend you not pay the fee out of pocket, but instead offer to allow them to deduct the fee from their loan proceeds. If they balk, you should walk.
Once you’ve paid the fee, if they do not extend the loan you would probably have little recourse, or it would cost you more than the amount of the fee to pursue recourse.