Creation of test users has been stopped for a long time now.

https://developers.facebook.com/docs/development/build-and-test/test-users

We are temporarily removing the ability for apps to create new test users. This should not affect existing test users. We will share an update once access to creating new test users has been reinstated.

You can edit and use the test user that was automatically created when the app was created.

Hi, I have the same problem too. When I try to create a new Test User, I receive the following message: "The ability to create test users is disabled temporarily".

No test users were created during the creation of the App and I cannot add any at this time.

Furthermore, I have also received a notice of restriction of the App if I do not provide these users to allow the functioning of the App to be verified.

I am extremely urgent to understand how to solve this problem otherwise my App will be blocked and users will no longer be able to log in.

Thank you for your support