Access lists specify the people in your organization who can create and edit maps in Google Maps Engine and who can view maps externally. To specify the people in an access list, you'll need provisioned users. You use the Google Admin console to manage users and user groups.
Google Maps Engine relies on Google Accounts for authentication, but it is possible to integrate with your own corporate identify management system. Integration may be set up by Google technical support engineers.
For information about provisioning users to your Google Apps domain, refer to the Google Apps Administrator Help.