Best bet is probably to get the full installer from Slitherine, via MY PAGE and then selecting "File Downloads" for the CMBN base game. This gives you the 3.4 GB full installer at v4.05.
If you go to "File Downloads" for any of the CMBN modules or packs, you get a v4.05 Multi DLC installer which is much smaller. Not sure though what this will do exactly.