UK players need to provide card details to claim free spins because casinos are required to verify the identity and age of their players by gambling regulations. Even if you’re not making a deposit right away, you’ll still be asked to register a card. By providing card details, the casino confirms that you are of legal age to gamble and that you are who you say you are.
Important: Adding your payment card for verification won’t affect your credit score, and it’s usually a one-time thing.