openvidu-ipcameras tutorial is a MVC application built with Java and Thymeleaf, which means that the client JS code won’t directly call the application server. The Java backend returns the HTML with the necessary OpenVidu Token already embedded in it (right here). If your app is not a traditional MVC app (the other common option is an SPA application that actually calls your applications server API with HTTP methods. Here you have a Microsoft post explaining these concepts just in case), then you just need to actively ask for an OpenVidu token to your .NET application server using JavaScript, consuming your application server endpoint (which needs to ask OpenVidu deployment for a Token and return it to the client).
I recommend reading the “Developing your video app” section of OpenVidu Docs: Developing your video app - OpenVidu Docs
As fot the OpenVidu endpoint, that is consumed when calling session.connect(TOKEN) right here.