Problem with adding user into User Management

[xoatk2025]

Hi guys, I'm trying to integrate with Spotify API.
User can login to my app through Spotify successfully but I can't use accessToken to call api due to error "Check settings on developer.spotify.com/dashboard, the user may not be registered."
I ensure that I add correct email of user into User Management ( email is copied from Edit Profile). I tried with owner account of Spotify Developer but it is failed too.
One more issue is that I use owner account of Spotify Developer to test SSO - it is success. Then I add an user into User Management list then I can't test SSO any more, callback url missing state field.
Feel free to check and respond me.
Thanks.