This was my first big KSP Project! Oh the memories... ^^
The idea is to bring 1 "Center Node" and 4 "Habitation Arms" in a low orbit around Mun (or of course anywhere else, but then you'll have to adjust the transport stages), dock them together and land the whole structure. You'll have to pay attention to aligning the docking ports correctly, otherwise your base will be twisted! Back in the day I did pay attention to balancing the arms, so the CoT should match the CoM after final assembly, but my fuel calculations at the time were... sub-optimal. If you assemble everything in a really low orbit (10ish km above Mun), you should be able to land everything, but your focus should be on maneuver efficiency! But don't worry, my fuel ran out some 10m above the surface of my target crater, but all those landing legs can buffer quite some landing. ;-) Also the final detachment of the landing modules could have used a little more attention to detail. But there's a small "Bulldozer" included that you can use to clean up all the landing debris afterwards again. ^^
The final assembly can host up to 40 Kerbals! There's also a huge and fancy beacon, which serves no purpose but looking good!
There's also a "v2" of both the center node and the arms included, which were developed and tested after the first iteration with a few optimizations, but the basic principle (and caveats) stay the same.
As this was built with stock only (and a few helper addons like Alarm Clock and Docking Cams), these things are not necessarily aerodynamic... You'll have to do some engineering on your own to use these things with Ferram Aerospace or Deadly Reentry.