NodeJS & OAuth2 expert to create login to a NodeJS application using an external OAuth server

Seeking a NodeJS and OAuth2 expert that can help create an SSO (single sign-on) solution. Users will log in to my NodeJS application using their credentials from an external website (controlled by me) that already has an OAuth server. Will also need assistance with use cases of fetching data through the REST API using the OAuth session. The website serving as the OAuth server runs the Invision Community Suite 4 (IPS4) software, which features an OAuth2 server and REST API. The NodeJS application to log in to is a game server application hosted on a different dedicated server. Details and possible solutions will be discussed with the awarded freelancer. If you have any questions, please do not hesitate to ask.