First, make a Mods folder in the game directory and keep in mind it works as an override. Next, you have to tell the sots.ini what to do with it by adjusting the Modules section
Mount1=Mods\Bastard Sword of the Stars 4.02
(Mount1 takes priority over Mount2 and Mount3)
Finally, unzip your BSOTS into its own folder (make sure it’s not a folder-in-a-folder, something we’ve all done when unzipping before) and drop it into your Mods folder.
That’s it - you’re good to go!