Not a problem. There are a few more steps than I like (and probably why so many people wish there was steam workshop support).
You need to have the Unity Mod Manager. https://www.nexusmods.com/site/mods/21
That can be installed anywhere, I think. You need to run it and search for Pathfinder. After it has found Pathfinder, it will modify it, and create a Mod Folder.
Then, installing the mod can be done in two ways. If you don’t want to unzip the mods, the Unity Mod Manager can be run instead. Use that to find the zip file, and it will install it to the mod folder.
Or, you can just unzip the file into the mod folder.
After that, when you start up the game, you should see a screen that shows you which mods are running and give you the option to turn them on or off.
Me, I just drop the newest version of the mod into the folder.
I’m running a few mods right now.
Turned Based Combat - Basically, it uses the Pathfinder Rules. Everyone goes one at a time, and you can see exactly the order that everyone moves. A lot of fights are made easier because of it.
Closer to Tabletop - Requires Turn-Based Combat - It makes the game plan more like table top. Which means, your Rogues are no longer supercharged with power because flanking is done properly. But, with turn-based, it’s also a bit easier to set up the flanking to begin with.
Eldritch Arcana - Brings in tabletop feats, the Oracle, but most interesting of all, Traits and Favored Class Bonuses. Traits are 2 mini feats you can select at the start of character creation, while favored class bonuses are a bonus you get (either plus one 1 hitpoint or plus 1 skill point) that you get for 1 class you have selected. It makes multiclassing a bit worse.
Call of the Wild - besides adding in the Hunter, the Witch, the Bloodrager, the Skald and the Warpriest, and a bunch of spells, feats and rages, it also brings in two nerfs (which kind of makes up for all the buffs that came with Eldritch Arcana). First, it nerfs Animal Companions a bit but gives them a few equipment slots. So, maybe not a total nerf. The second thing is, it sets everyone to half the skill points the have in P and P. This is because most Kingmaker Skills would be 2 skills in P and P. The original game already gives everyone fewer skill points per level, but not exactly half. So, its a little bit of a nerf, but with the traits and the bonus skill point per level, it really levels out.
Specialization - This is the final mod that I installed, and I haven’t actually used it yet. Basically, for 1,000 gold, you can rebuild any NPC. Sadly, its the only way to give NPC Traits, and Favored Class Bonuses. I hate that it’s a 1,000 gold.
Although I guess you could give yourself more money with Bag of Tricks but I haven’t installed that.
Okay, so I might have gone overboard. If you stick to Turn-Based and maybe Closer to Table Top, you really get some better gameplay. Don’t worry about the rest. What is nice, is that they all work together without any trouble. So far.