https://support.okta.com/help/s/article/GitHub-Enterprise-Cloud-Organization-fails-to-provision-users-with-the-error-Automatic-provisioning-of-user-name-to-app-Github-Enterprise-Cloud-Organization-failed-Error-while-creating-user-username-Not-Found-Errors-reported-by-remote-server?language=en_US
추가로 깃허브 어플리케이션 Provisioning 설정에서 Provisioning to App의 옵션값을 모두 Enable해야함