All users are automatically added to the "public" group.
For normal users, staff/admin users can create further users via the admin interface. This is "/admin" after the URL, eg: https://variantgrid.com/admin/ (need to change to your server obviously)
In the "Authentication and Authorization" section, there's a line with "Users" - click the "+ Add" link, then enter the user/details. Groups
You may want to add people to different groups so they can share data between themselves.
Users, permissions and groups
User / Lab Assignment
LDAP (Lightweight Directory Access Protocol) is the protocol behind Microsoft Active Directory, which is what most corporate intranets use for logins, Outlook, shared drives etc.
See Wiki: LDAP Setup