Ideally they accept Monero and do unlinkable payments but I doubt they will accept Monero. Hopefully they accept some crypto.
That is not the same thing.
You buy a Mullvad scratch card on Amazon and you redeem the token string.
Mullvad also offer the option to put your card number into the Mullvad website, and I'm sure many privacy conscious people would be very reluctant to do that.
Card payments these days leave far too big a trail. The bank knows, the intermediary (e.g. Stripe) knows, and the merchant (e.g. Mullvad) has to keep records for accounting/tax requirements.
Molly is going to add a Monero integration while also having various other advantages.
They don't accept crypto donations directly or accept them for their backups so I assume they wont for registration.
If they accept monero or something then ok but I doubt they will.