I need to the download a forum that members only log in.

I already tried capture URL and browser said my login details were captured
and I could return to HTTrack. But when open the browse mirrored website and
access a topic, it says you are not logged in and not have permission to view
topic. All that happened it downloaded the public section of the site, but I
need the members one to be saved too. Can anyone help with that?
Very much thank you
Xentos