Have you gotten it working with DOT all in the same server? Start with that.
I have not used DOT as an external OAuth2 AS, but only as a client to en external AS that my organization runs. In that case, I had to configure an introspection client and secret. When using an external DOT instance, you have to configure an access token I believe.
In settings I've added 'oauth2_provider' in INSTALLED_APPS[] and the external AS URL and credentials as shown
here.
Something like this:
Note that you'll need to set an expiration date and time that are reasonably far in the future.