My PC initially blocked not only AdventurOS but another program that apparently runs in the background and is probably responsible for tracking your folders. At first I had the same issue where it generated just a single room with no doors. After I allowed access to both of these programs, the generation worked fine.
Like I originally wrote, there are 2 programs that need access to your PC. One is adventurOS and one is something that also pops up the moment you start the game (don't remember what it's called, just check your Task Manager). Either your Windows or your Antivirus is blocking those and you need to manually allow them access to your PC.