This download looks like a lua file. You need to place it in your lua folder inside the Garry's Mod folder.
You should end up with a directory structure similar to below:
-
steamapps
-
common
-
garrysmod
-
garrysmod
-
lua
-
autorun
- screenshots/
- gm_construct0001.jpg
- gm_construct0002.jpg
- gm_construct0003.jpg
- gm_construct0004.jpg
- gm_construct0005.jpg
- Reed Me.txt
- Addons/
- universe_gate/
- info.txt
- lua/
- entities/
- stargate_universe/
- cl_init.lua
- init.lua
- modules/
- shared.lua
- materials/
- models/
- Flyboi/
- sgu_gate/
- Ancient_metal.vmt
- Ancient_metal.vtf
- mur00.vmt
- mur00.vtf
- SGU_gate-main.vmt
- SGU_gate-main.vtf
- SGU_gate-main_bump.vtf
- white002.vmt
- sgu_gate_effect/
- Ancient_metal.vmt
- Ancient_metal.vtf
- mur00.vmt
- mur00.vtf
- SGU_gate-main.vmt
- SGU_gate-main.vtf
- SGU_gate-main_bump.vtf
- white002.vmt
- VGUI/
- entities/
- stargate_universe.vmt
- stargate_universe.vtf
- models/
- Flyboi/
- sgu_gate/
- sgu_gate.dx80.vtx
- sgu_gate.dx90.vtx
- sgu_gate.mdl
- sgu_gate.phy
- sgu_gate.sw.vtx
- sgu_gate.vvd
- sgu_gate_effect/
- sgu_gate.dx80.vtx
- sgu_gate.dx90.vtx
- sgu_gate.mdl
- sgu_gate.sw.vtx
- sgu_gate.vvd
- sgtbase.dx80.vtx
- sgtbase.dx90.vtx
- sgtbase.mdl
- sgtbase.phy
- sgtbase.sw.vtx
- sgtbase.vvd
- sgtbase.xbox.vtx
- sound/
- chevron.mp3
- dial_fail.mp3
- gate_close.mp3
- gate_open.mp3
- gate_travel.mp3
- stargate/
- universe/
- Chevron.mp3
- Chevron2.mp3
- Chevron_lock.mp3
- chevron_long.mp3
- Gate_Close.mp3
- Gate_Open.mp3
- Gate_Roll.mp3
- Just_Chevron.mp3
- Long_Gate_Roll.mp3
- Stargate Begin Roll.mp3
