Hi @Nico Felten ,
You can also use a debit card if you don't own a credit card for the Azure free trial account.
https://azure.microsoft.com/en-us/free/free-account-faq
What do I need to sign up for a free account?
All you need is a phone number, a credit card or a debit card, and a Microsoft account or a GitHub account.
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, thank you!
Best regards,
Leon