You can import users from an LDAP server or uniFLOW server. You cannot add a [User role] to an imported user. When you add the user to a user group, the user receives the role of the user group. You also can only change the default group of an imported user amongst the groups it belongs to in the LDAP server. Also, you cannot change its password.
To be able to import groups or users from a server, the test connection should be successful.