Hi Xavier,
As per checkingthe free 3‑month PC Game Pass token is only available under certain promotional conditions, and one of the key requirements is that recurring billing must be enabled. Please note that this isn’t a general benefit for all accounts since it’s tied to specific offers where Microsoft requires recurring billing to be turned on so the subscription continues after the free period.
If in case you don't have recurring billing enabled, you won't be able to claim the promotion.