Make sure to first have SuperBLT installed. Click the link in the dependency list.
Optional video tutorial for installing SuperBLT, BeardLib, and mod_overrides mods: https://youtu.be/rin_sjSJIkg
After downloading the mod, use a program such as 7zip to extract the main folder of the mod. Drop that folder into the mods folder which is supposed to be in the game's installation folder.