Note: This DLC does not work for Traditional Chinese locales.
1. Install the game via Steam
2. Make sure to run it (get to Start, play through a cutscene or two)
3. Close the game
4. Open the installer from your download folder. Depending on your version of Windows, it may prompt you to run anyway (bypassing SafeScreen) and warn you it's an unknown publisher. Click yes to install anyway
5. Let the installer run.
6. It's installed!