OAuth2 not working


I use a custom OAuth2 Provider to auth users on my Odoo instance, but, the process not totally working. 

The token request and the code verification work, but the login doesn't work, only one message appears, "Access denied".

I think the problem is with user profile data, Odoo isn't creating a new user or logging in existing users from oauth2.

Does the user need to be created in Odoo before, or can Odoo create users from oauth 2 ? If, yes, what data is expected ?
What data are expected in an oauth2 profile ?

Thanks & Regards