Choose only ONE .pak among all the folders.

01 Replace the default dark black coat for a black/no marks one
02 Replace the default light black coat for a black/no marks one
03 Replace the default grey coat for a black/no marks one. Tulpar and Sleipnir will become grey instead (all "light black" horses will turn grey) for keep coats diversity.
04 Replace the default white coat for a black/no marks one. Change the default light black coats (buyable ones Tulpar and Sleipnir) for default white coats.

Simply Extract files and put the .pak you want into the following folders:
KingdomComeDeliverance\Data\_fastload
KingdomComeDeliverance\Data
(If you're under steam you'll find this in C:\Program Files (x86)\Steam\steamapps\common\)
Don't forget to put the .pak in BOTH path