Install with the easy to use Flagrum Mod Manager:
https://github.com/Kizari/Flagrum/releases

Flagrum:
Open Flagrum Mod Manager, click "Install from ZIP" and select the mod.
https://github.com/Kizari/Flagrum/wiki/Using-the-Mod-Manager

Manually:
Unpack the "*_manual.zip", copy the contents to your games root folder and overwrite when prompted.