How to secure streamlit application link deployed in google cloud kubernetes

I’ve managed to deploy my streamlit application to the google cloud. I used Loadbalancer service which gives me a public address to access the application.

Now the next issue I am facing is how to secure the link? I followed the official guide which mentions using oauth2-proxy, however, it is not detailed enough. For example, how to get REDIRECT_URL, GOOGLE_CLIENT_SECRET etc?
Deploy Streamlit using Kubernetes - Streamlit Docs.