Steps to use widget:

1)  Generate new OAuth api client id for your site here: https://console.developers.google.com/apis/credentials

2) Set the site property 'ClientId' to that value you just generated.

3) Drag 'GoogleSignIn' block to your screen and configure the input parameters as desired.

When the notify action from this block is triggered, the get message will be the email that is attempting to sign-in. The widget will only notify an email back after it has already been authenticated via google.