Using OAuth 2.0 to authenticate resource

Hi folks,
I'm currently trying to set up OAuth 2.0 authentication on a resource. My resource is a GraphQL endpoint hosted using Google Cloud Functions. I've followed the docs in order to create a client id and secret from the Credentials - APIs and services section of GCP. I've also added in the client id and secret into the Resource section, along with the Authorization header with value Bearer OAUTH2_TOKEN.
However, I'm not sure what to do next - whenever I run a query that is using this particular resource, I'm getting 401 Unauthorized. I don't think the OAuth flow is being triggered - so an access token isn't being fetched. Can anyone help ?

Hi @mitch8231, If you click 'Test Oauth Integration with your own account' are you able to successfully complete the auth flow? If so can you then click 'See token status' and confirm that you fetched an access token?\