Yes,you need to download everything
This is needed to switch the new maps on or off with JSGME>
IL-2/jsgmemods/#UP3RC4_MapExpansion
The SFS Files that are contained in the SAS_SFS and DBW_SFS folders are also all needed with all SFS Files
The maps themselves are contained in these SFS Files>
IL-2/SAS_DBW
IL-2/SAS_SFS
Doesn't really matter,
but these questions would have been better posted in the actual map expansion thread
rather than starting a new thread