Hi Thor,
You will need to enter a credit card to use a VM (you should have had to enter a credit card to sign up for Azure Free).
If you do sign up for Azure Free, you will get $200 USD in credits. After you use them, or 30 days passes, you will be asked to change to pay-as-you-go and won't be charged unless you do so.
Add, update, or delete a payment method
"The supported payment methods for Microsoft Azure are credit cards, debit cards, and wire transfer. To get approved to pay by wire transfer, see Pay for your Azure subscription wire transfer."
https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/change-credit-card
If this is helpful please accept answer.