Here are the steps to install the lua libs on your server : 

If your server is running on a Linux system : 
- Unzip lua_libs.zip
- Copy the 'liblua5.1.so' file (lua_libs/linux) and place it in your server root (usually were 	the etmain folder is located)

If your server is running on a Windows system ( !! WINDOWS SERVERS WILL NOT START WITHOUT LUA FILES !! ) : 
- Unzip lua_libs.zip
- Copy the 'lua5.1.dll' and 'lua51.dll' files (lua_libs/win32) and place it in your server root (usually were 	the etmain folder is located)

After copying the correct files, start your server.
Set the "lua_modules" cvar to use lua scripts on your server (Read more in N!tmod documentation).