Larian Studios Forums Divinity - Original Sin Divinity Original Sin - Mods [WIP] Journey of the Lone Wolf

Because it isn't a .pak file, the files in the ZIP go into the corresponding folders in your Divinity installation path (wherever you have installed to). For my game, I would install it by placing the Data folder into the C:\Program Files (x86)\Steam\steamapps\common\Divinity - Original Sin\ location and merging the Data folders together.