First you need RESOREP available here:

https://www.undertow.club/downloads/resorep.1254/

Watch a tutorial here:

https://www.youtube.com/watch?v=_QjnLKXErBg

Unpack the mod file anywhere you want and you'll have two zip files.

One zip file is unpacked in your Resorep modded texture folder.
The other goes in the games "localdata" folder.

You should end up with this file structure:

...Steam\steamapps\common\GreedFall\datalocal\equipment\hum\hea\textures

Once that's all in place, run Resorep according to the tutorial and the mod should work.