Hi,
Note that it also depends on the FS version.
FS9 always has a "Modules" folder, even when it's empty, and (most?) FS9-compatible versions of FSUIPC require manual extracton of files in that folder.
FSX (to my great and recent surprise) does not create a "Modules" folder on install, but the latest FSX-compatible version of FSUIPC has an installer that also creates this folder if it does not exist.
Hope this helps
Andrei