Hello Diego,
Welcome to Microsoft Q&A forum.
Based on what you described, I believe that this was some issue regarding your payment method. This happens quite often if you trying to make the first purchase or changing the payment method. This happens on multiple platform, not just Xbox apps.
Please note that this is a user-to-user support forum. Moderators, contributors including external Microsoft employees cannot directly intervene in Microsoft product features or access back-end systems. Our role is limited to providing technical guidance on reported issues, requests, or ideas. As the instruction has told you, you will need to contact Microsoft Support to resolve this, you can try to follow these steps to see if you can contact a person.
- Type Live chat in the search box.
- Now click Get help, and Select Contact Support or Sign in to contact support below.
- Go to the Products and services tab, and choose Other products
- On the Category tab, choose Billing and Account Profile questions
- Go to Confirm.
- You can now choose the option of Chat with a support agent on your web browser.
Thank you for your understanding.