Its quite simple. Usually involves installing to steam library, common files, m&b warband, modules folder... Only started getting into it in the past 2 months. Going nuts.
Best you figure out the 'ultimate' combination and play from that. I did 150 days on Gekukojo before I realized theres that Seburojo or whatever mod which again makes it quite different from the original 3.0. And they released a new version of that which is not save compatible.
Also playing the 1.05 Brytenwalda plus. I mean, the game is great and I did about 150 days of that but I realized I'm going to restart with this new version. If you got all the time, play them all of course.
But yeah, you want to somehow open it up, unzip and copy it into modules folder. Might need to install into that folder with some of the installers though.