Most of the maps you see that aren't from FH itself belong to rps. Granted a few are public, but the majority, nay. Thus, you have to join said rp before you're permitted to download their map. The owners worked hard to have a place for their group, and them alone, and don't make the maps publicly downloadable.
Right now there's a map called ElderCircle up on the bar. I'm in the group it belongs to. They have a website which they put the link on, so that it'd be hidden. Sometimes, though, groups will put the link in either the leader's or group's bio, in which case if I'm going to join, I'll usually download it in advance.