G-suite Integration with a web application Google workspace

Question

I am currently developing a web application using .net core which will be integrated with gsuite. I've successfullly configured gsuite marketplace sdk. The application will only be installed by domain administrators. So there will be no individual installation. We will be using service account with domain-wide delegation to impersonate users. I published the project to only my domain for testing purposes. I have installed the application from gsuite marketplace. After installation, I saw access has been granted for the requested scopes. So far so good. After all those steps, when I click to "Launch" button, the button redirects me to the application website, which is fine. But, I dont know how to authorize the admin user to my web application. I have found OpenID connect, but i'm not sure. I could not have find a documentation, I'm lost. Can you suggest me a way?