sent_gateringv1point2.zip

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
          • sent_gatering <-- Addon folder!
            • e.g.
            • lua
            • maps
            • materials
            • models
            • etc

• sent_gatering/
  • cl_init.lua
  • init.lua
  • shared.lua

Mashilo (ましろ) , rionjasper, lasteagleknight, sisa.d, Der Master, PUMPUMBOW, FuzzyLeo, Caseythatisntepic