Visit mod’s page and click the Subscribe button (you should be logged in).Find the desired mod at Total War: ROME II Workshop page.Consider older versions if you have any compatibility issues.
Just launch it after copying mod files and enable desired mods. It is possible to avoid file editing routine with Total War Mod Manager by mitchwc. Firstly, you need to navigate to Options -> Mods from the main menu, then make sure that Run “movie” and “release” pack mods and Run user script mods are enabled (restart the game to apply).