Before you start, make sure you have connected Firebase to your Webdraw App.
If you haven’t, you can do so here.
Step 1: Ask Webdraw to add the Login with Google button to your app
Use your Firebase prompt and ask Webdraw to add a “Login with Google” button to your app. Here is an example prompt you could use:
Login with Google prompt example
App button to generate the app, i got this already working app:

Login with Google app

After clicking the login with Google button and selecting my account
If this is the first time you are using Firebase, you probably need to configure
your Firebase project to allow logging in from your App, so look into Step 2.
Step 2 (optional): Ensure your Firebase project configuration allows logging in from your App
To do this, you can go to the Firebase Console -> Build -> Authentication. If you have never done this, click on the “Get started” button.
Firebase Authentication

Enable Google sign-in method
*.webdraw.app domain listed, click on the “Add domain”
button and add your domain.
Now, your App should be fully configured to Login with Google.