Using Google OAuth2 your teachers and students can log in with their Google or GSuite email addresses.
From the dashboard the site administrator should choose:
Other Admin
And then from the resulting screen choose :
Google OAuth2 Credentials
On the following page you should enter your
- Client ID
- Client Secret
- Allowed Domains (optional)
You can get those from Google. See the following document for information on how to do that:
https://docs.moodle.org/402/en/OAuth_2_Google_service