I fixed 2 things for you aVoN.
The problem for why it wasn't loading was the module. It was in lua/include/modules, when it should have been in lua/includes/modules.
Also, I noticed you missed out quite a few source mods that are on Steam, so I have edited one of the .luas to fix it. Here is the chunk that I edited:
-- Currently copy & paste from the old enhanced-gm_mount by SteveUk. later my addon will find all your games dynamically
local AdditionalContent = {
ageofchivalry = {title = "Age of Chivalry",depotid = 17510},
mm = {title = "Dark Messiah",depotid = {2100,2130}},
diprip = {title = "D.I.P.R.I.P. Warm Up",depotid = 17530},
dystopia = {title = "Dystopia",depotid = 17580},
esmod = {title = "Eternal Silence",depotid = 17550},
insurgency = {title = "Insurgency Modern Infantry Combat",depotid = 17700},
left4dead = {title = "Left 4 Dead",depotid = 500,vpk = "pak01_dir.vpk"},
left4dead2 = {title = "Left 4 Dead 2",depotid = 550,vpk = "pak01_dir.vpk"},
pvkii = {title = "Pirates, Vikings, and Knights II",depotid = 17570},
se1 = {title = "SiN Episodes",depotid = 1300},
smashball = {title = "Smashball",depotid = 17730},
synergy = {title = "Synergy",depotid = 17520},
ship = {title = "The Ship",depotid = 2400},
zps = {title = "Zombie Panic! Source",depotid = 17500},
}
That goes into mount2.lua, and I think you can tell where in it.