This page explains how Google Sign In is handled by Helpjuice.

Google allows companies to have their own domain in their e-mails, like e-mails @helpjuice.com. This feature can be used by Helpjuice's clients to create/authenticate accounts.

This is how Helpjuice a Sign In callback from Google:

1. If there's a user with the exact e-mail authenticated through Google, just sign him in and send him to the Dashboard;
2. Otherwise, the system looks at his e-mail and searches for the domain, like @helpjuice.com;
3. If there's an account associated with that domain (like helpjuice.com), the system will create a user with that e-mail, sign him in and send him to Helpjuice

To associate an account with a Google domain, an Admin from that account must go to Settings and fill the Google Apps Domain field.

Newly created users via Google Sign In are automatically set as Viewers for security reasons. Therefore, they won't be able to change anything within their Knowledge Base, they'll just be able to read it.