Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hello
Go to your Microsoft account https://account.live.com
Go to Your info, make sure the language field is not blank. Set it up correctly. This is typically the culprit of not being able to set up billing address. Once the language field is filled in, check Billing and Shipping addresses, make sure you have them set up correctly too.
Then try to reactivate credits again.