This is just a repack of Garry's Mod 9.0.4. No need to use the installer. Just put the folder inside of this ZIP into "sourcemods" folder of your Steam...
An old version of Garry's mod that can be runned through Steam as a sourcemod and has working multiplayer. Please, read the description.
You can tag anything on ModDB on ModDB, and all tags can be voted up/down by the community depending on their relevance.
Official tags, as well as up-voted tags will appear higher in the list as they are deemed the most relevant.
If you discover a page that does not have any tags applied, why not help out the community by submitting tags, or posting a comment with #tags in it, which will be automatically linked.