Bitwarden Splunk App - Self-Hosted

Having issues connecting the Bitwarden Splunk app to my self-hosted Bitwarden server. Has anyone got Splunk to successfully work with your self-hosted install?

Seeing the following errors in Bitwarden Logs:
400 Client Error: Bad Request for url: https://*myvault.*com/identity/connect/token

Do I need to enable something different for the API to work?

The setup docs reference using the Org API bit I do not have that option, only my user API token, is that the issue?