Navigate to: %appdata%\The Creative Assembly\Attila\scripts\ . Create or open a text file named user.script.txt .
Launch the manager and set the "Game Directory" to your Attila folder. Navigate to: %appdata%\The Creative Assembly\Attila\scripts\
: Copy all downloaded .pack files directly into your Total War: Attila data folder. Navigate to: %appdata%\The Creative Assembly\Attila\scripts\