This download looks like a map. You need to place it in your maps 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.
LntLethaL, Luiselektronik, nokisajar, Pixelbrain, Piniie, [FLC]Sandro, Madgonian, Wero1302, じょえもん, (-C-)Logge, DigiBaer, AaronG5, AaronG5, BasGameZ, CaptainQ, Mr. Maćko PL, Arkror, Xenn, Kupfersohn, kobayr5, Keatrix, PUNCHINGD3IK, [SIB] Wehrmaus 防衛マウス, Sergeant Yoshi, Bruiser, Stickman, Zerpent | KrixGaming, Mr.Affro, MCrackLP, FrauFörster, Shinfekta, bashir, Rypeax DotaX2.com, Celica, The Husky, Raddy, Atropus, tommy, frangelCraft, theonlyOn3, .Exe, Mr.Winchester, Taiiden, hardcoregamerc1, Mr. Tom, mindy, Czyborra, TheNoobSkywalker, JonasC., Sir Cntingham +2575 others
