I am new to modding, I tried adding to add this to my game to dip my toes but no new zombies are spawning. I have put the mod in the mods folder in app data like you said, have made sure EAC is turned off but still not working. I am using latest stable version of 7 days. I looked in the debug menu and the new zombies are listed there, but not spawning in the world.
Update, I am seeing them now but rarely, is the spawn related to level or day? this is a new world but I am only seeing a few driving around for long time