Welcome to the Auth0 Community!
I’ve checked your tenant logs, and you’ve 2 database connections enabled on your tenant, one of which is a custom database and one that uses an Auth0 database. To fix your issue, you would need:
a) Hint Auth0 to which database is should attempt to log the user in against
You can provide this via the
connectionparameter in the /authorize request indicating the name of the connection the user should be logged in against.
b) Disable the custom db connection.
Thanks
Dawid