It is not needed, because this mod only supports headset. No controllers. So you need to play with controller (for example xbox)
Edit:
Also after little bit of research I found out, that R.E.A.L. mod developer tried to get it working on fivem, but because of d3d11.dll it can not be done (link: Any plan/is it possible to add support for fivem, or know of a way to get it working? · Issue #34 · LukeRoss00/gta5-real-mod · GitHub) and also because of servers blacklisting mods in clients.
I think it would be possible to get it working, but developers of fivem and R.E.A.L. need to cooperate.