As Gerald said, what you need to do is to configure the sync section of the LDAP configuration in your config.pm like the following

# agent data sync against ldap
     $Self->{'AuthSyncModule'} = 'Kernel::System::Auth::Sync::LDAP';
     $Self->{'AuthSyncModule::LDAP::Host'} = 'ldap://ldap.ip.address';
     $Self->{'AuthSyncModule::LDAP::BaseDN'} = 'DC=Domain,DC=example,DC=com';
     $Self->{'AuthSyncModule::LDAP::SearchUserDN'} = 'user';
     $Self->{'AuthSyncModule::LDAP::UID'} ='sAMAccountName';
     #$Self->{'AuthSyncModule::LDAP::UID'} ='cn';
     $Self->{'AuthSyncModule::LDAP::SearchUserPw'} = 'SearchUser';
     $Self->{'AuthSyncModule::LDAP::UserSyncMap'} = {
   # DB -> LDAP
         UserFirstname => 'givenName',
         UserLastname  => 'sn',
         UserEmail     => 'mail',
    };