auto-creating new users in Discourse?

Problem/Motivation

I'd like new Discourse accounts to be created when a new Drupal user is created.

Steps to reproduce

Turn on SSO in Discourse as described on the project page.
Create a new user called Bob in Drupal.
Result : Drupal logs show an error, Discourse not synchronized. User Bob does not exist.

Proposed resolution

When a new user is created in Drupal, create a matching new user in Discourse.

If this typically works, are there settings I need to adjust? In Discourse, I've turned off Invite Only and enabled Allow New Registrations. Are there any other settings in Discourse that would affect this?

Thank you!