Google Assistant SDK - OAuth Client Was Not Found

I’m getting the following error when setting up the Google Assistant SDK

The OAuth client was not found.

If you are a developer of this app, see [error details](https://accounts.google.com/).

Error 401: invalid_client

I already have the regular Google Assistant and Nest integrations configured and working. In the instructions, it was not clear to me if I would be able to use the existing credentials that I had configured for the regular Google Assistant integration, although I don’t see any way to use separate credentials.

Bump, anyone have any troubleshooting suggestions?

please please halp