In addition to the user authentication provided by Bookeo, you can also use single sign-on to authenticate your users outside of Bookeo.
Bookeo integrates with Google Apps SSO. You can learn how to set up single sign-on for managed Google Accounts using third-party Identity providers here https://support.google.com/a/answer/60224?hl=en
Therefore, account users can sign into Bookeo from the SIGN IN page either entering their Bookeo username and password, or using their Google Apps SSO.