OK, let me shed some light on this menu. I don't know why this thing is here. It's not a hack AT ALL!
It's a basic mod menu, designed for an external MP mod (which is really cool btw, checkout FiveM )
This MP mod has separate servers, handled like Garry's Mod, Arma 3, ..ect.
These servers can have mods on them streamed to the client, but they also can allow for people to bring their own .asi scripts to a server via a legit server option.
The install instructions are for a special folder inside the mod because FiveM installs outside the game, meaning you can have FiveM and still go to GTA:O without any issues.
So yeah, I am sorry folks, its not a hack, and I have to admit, despite it saying [FiveM], it can be very confusing to someone who doesn't even know what FiveM is. So yeah, this menu being here is very silly and very pointless since its pinned on the FiveM forums (where this thing belongs and should stay).