When you start with SS 6.4 (I believe is the last) you will be forced to choose a submod. I forget its name, but there is one that says: "most players choose this one" I believe it's a balanced submod between aggressive AI and backstabbing by other factions. I'd start there.
There are a few other submods there; one is rather complex; it combines a supply to movement adaptation to the game and I'd not recommend you go into that one to begin.
Choosing the submod is IMPORTANT, all of your subsequent campaigns will play under that set of rules for the AI.
To change that, reinstall (no uninstall necessary) and choose different submod.
Also, I had to go through the initial SS 6.4 installation steps 2-3 times (for whatever) reason to get the game to load. So if you need to walk through all the steps again; the mod works.
GL
* search for rotbaron in their forum, you'll find/see my learning curve with SS 6.4. Maybe that will help if you get stuck.