Dear Seunokewoye,
Good day! Thank you for posting to Microsoft Community. We are happy to assist you.
As per the description you have shared, we understand that you have a concern with adding new payment method in Microsoft 365 admin center.
We do understand your query here but, as your query related to payment and credit card, and since we are belong to Microsoft Community site and our site is available for public, we have limited resource and privilege to examine subscription payment and method related scenarios. Since you entered the correct address for your credit card, you may check and confirm that your credit card and your tenant country are the same. At this point, we sincerely recommend you contact our dedicated billing support team via Get support - Microsoft 365 admin | Microsoft Learn. In this way, our dedicated billing support team will check your tenant and credit card information and assist you further.
Thank you for your time and understanding. For other questions, feel free to add your post in the Microsoft Community team.
Stay safe and healthy. Have a good day!
Sincerely,
Libeamlak | Microsoft Community Moderator