Can I use Captive Portal and the Directory Connector UNLS?

Yes, provided you make sure to keep them separate. Users should not be logging in with Captive Portal authentication set to Active Directory and also be running the UNLS or ADLM simultaneously. If they are both used, NG Firewall uses the most recent information to determine the correct username. This can be very confusing as the UNLS updates on login (and every few minutes) and the Captive Portal users will also login after every timeout, sometimes with a different username.