Create a folder with it inside and set it at the fivem-lua-linter.luacheckPath setting.
Run it using LuaRocks.
Now you have to create a folder which will be used to provide the LUA content with required data to reduce the amount of false warnings the linter would raise.
After creating it, set it at the fivem-lua-linter.luaContentPath setting.
As this tool has been developed with some exclusive ESX framework in mind, i left some room which allows you to provide .lua files to the linter so it doesn't raise errors or warnings at the functions present in those .lua files.
You can do that placing framework LUA files inside the LUA Content folder at esx/client (For client only imported functions) and esx/server (For server only imported functions).
With that in mind, we also have to provide a LUA file with the FiveM natives definitions too so the linter will be able to identify them and don't raise warnings about them.
You can get the natives_universal.lua from your FiveM client at FiveM.app\citizen\scripting\lua and you should paste it at the LUA Content folder inside a folder called natives. The final path for it should be: lua_content/natives/natives_universal.lua.