How to add more Fretta Playermodels?

Hello, I’ve been trying to add playermodels to my fretta server, so they will be available to use for gamemodes such as Deathrun. (IP:
The players im attempting to get to work with the fretta gamemode are these -->

I have tried placing it into my addons folder and even taking the files from inside and putting it in /garrysmod/garrysmod
I want to be able to have a few custom playermodels, but i cannot seem to get the playermodels to appear on the fretta playermodel selection screen.

Your help will be much appreciated!