Free spins themselves do not technically have wagering requirements. It is the winnings that do.
If your free spins wins come in the form of bonus money, it is important to understand that this is separate to cash. You will need to meet a wagering req, for instance of 40x wagering or 50x wagering, to withdraw your winnings.
Note: There are no deposit no wagering spins, and these offers come in the form of real money.