This plugin is not compatible with DB-less mode.
For its regular work, the plugin needs to both generate and delete tokens, and commit those changes to the database, which is not compatible with DB-less.
In addition to this, its Admin API endpoints offer several POST, PATCH, PUT, and DELETE methods for tokens and credentials. None of them would work on DB-less.
The OAuth 2.0 Authentication plugin is compatible with the following protocols:
Here's a list of all the parameters which can be used in this plugin's configuration: