This download looks like a save. You need to place it in your saves folder inside the Garry's Mod folder.
You should end up with a directory structure similar to below:
Don't know where the Garry's Mod folder is or how to extract zip files? See more useful installation tips.
Crypto Currency, Player, Karma Khix, mossesx, GLITCH, deivis_salaverria_hernandez, 1_mcm, jond0000, [GL} Buk Changlo, KIRILLUREV, Dome TH Love Emilia, marius44422, pdaniel030609, [GAR] Donut2332, luke.5.3.2002, ozike21, josh, Mario89, ⓁⓔⓞⒹⒻⓈⓉ, MikeyMatou (No Bunnyhop), trooperstorm111, mcpro.deejay44, Bill Cipher, jannes.van.rue