Hm it should work and yes you've to put it into the addon folder C:\Program Files (x86)\Steam\SteamApps\common\left 4 dead 2\left4dead2\addons
It works on the first map of the Swamp Fever campaign note you can subscribe to it on the steam workshop for it to work better I posted it on here just cause I don't want people reuploading my mod I dont have time to deal with it lmk if there are any more problems cheers

Thanks for the stars mate it means a lot