VW Golf Mk.II by TDM

This download looks like an addon. You need to extract the downloaded zip and put the addon folder in your Garry's Mod addons folder. You should end up with a directory structure similar to below:

• steamapps
  • common
    • garrysmod
      • garrysmod
        • addons
          • VW Golf MKII by TheDanishMaster <-- Addon folder!
            • e.g.
            • lua
            • maps
            • materials
            • models
            • etc

• VW Golf MKII by TheDanishMaster/
  • info.txt
  • lua/
    • autorun/
      • tdmcars_mk2.lua
  • materials/
    • models/
      • tdmcars/
        • mk2/
          • black.vmt
          • black.vtf
          • glass.vmt
          • glass.vtf
          • grille.vmt
          • grille.vtf
          • interior.vmt
          • interior.vtf
          • lights.vmt
          • lights.vtf
          • lol.vmt
          • lol.vtf
          • nodamage.vmt
          • nodamage.vtf
          • nodamage1.vmt
          • nodamage1.vtf
          • nodamage2.vmt
          • nodamage2.vtf
          • nodamage3.vmt
          • nodamage3.vtf
          • nodamage4.vmt
          • nodamage4.vtf
          • nodamage5.vmt
          • nodamage5.vtf
          • tirea0.vmt
          • tirea0.vtf
          • tirea0_bump.vtf
          • undercarriage.vmt
          • undercarriage.vtf
          • undercarriage_bump.vtf
          • wheel.vmt
          • wheel.vtf
  • models/
    • tdmcars/
      • golf_mk2.dx80.vtx
      • golf_mk2.dx90.vtx
      • golf_mk2.mdl
      • golf_mk2.phy
      • golf_mk2.sw.vtx
      • golf_mk2.vvd
  • scripts/
    • vehicles/
      • TDMCars/
        • golfmk2.txt

Wallabee, milosspasev, Lux, palagizz., piotr, Ati (∩ ͡° ͜ʖ ͡°)⊃, joksimovicstrahinja80, booniecolf, aliayaz07732, jamesbuckley121, _XVIRUS, andrejstevanovic327, Valentinohaker, ttoni0228, Hermes, gamerdzpro2005, SIM2005, Bonntman, woyvqcezawidsljxau, deividas.andriulis15051505, papilipu1, malgosiabartkowicz, kubalat2008Key-Drop.pl, ☣︎MkS➌︎➍︎➍︎☣, uguandahklukles, angeldavidpardoromero, zgame3334, skateord65, Brinyiczki, pulamea917, PatatesYiyenPattis, boilong, matekuz1 `Key-Drop.pl`, koper22xdd Key-Drop.pl, HNoel, gusanitaherizona, carmelomale666, WINDEX!, andrzej_masXD, pclentos1500, luizo28, alandiegobr5, PC57010, jakehinks1234, Carl Johnson, KERIK, 2170136760, Tom Cruisader, akinakcan94, Elver_d_mg +1554 others