Setting up Google Authentication

Create a Firebase project here: https://firebase.google.com/. You'll need a signed Android build for that, that can be a debug self-signed build too, just retrieve the signing hash. The key hash of an already signed ap can be obtained as follows (on macOS): keytool -list -printcert -jarfile the-app.apk
Place the generated google-services.json file in android/app for Android and the GoogleService-Info.plist into ios/app for iOS (you can stop at that step, no need for the driver and the code changes they suggest in the wizard).
You may want to exclude these files in YOUR GIT config (do not exclude them in the .gitignore of the application itself!).
Your web client ID is auto generated during the Firebase project creation. Find them in the Google Developer console (https://console.developers.google.com/)
Make sure your config reflects this ID by setting googleApiApplicationClientID in config.js.
Add your iOS client ID (the REVERSED_CLIENT_ID in the plist file) as an application URL schema into ios/app/src/Info.plist (replacing placeholder).
Enable YouTube API access on the developer console (see above) to enable live streaming.