How can I launch this Agora WebRTC sample node.js server?

I'm node.js beginner and try to use Agora WebRTC SDK with reading this document.

https://docs.agora.io/en/user_guide/communication/webrtc_user_guide_communication.html#qs-communication-webrtc

Regarding sever topic in this Document, At first, I used "npm install" command to make nodo_modules. Next, I check APP_ID and APP_CERTIFICATE in ./server/nodejs/DemoServer.js. But I could not find them. APP_ID is VENDOR_KEY in DemoServer.js?

Please help me to launch this sample.

via Koki Yanagiya