Supplement - United States Civilization

How to activate the code?

From the Microsoft Store:

To claim your content, open your Windows 10 or 11 device and search for "Microsoft Store".
Make sure you´re signed into the Microsoft Store with the account you want to play Age of Empires III: Definitive Edition with, then click the account button in the top right corner next to the search bar.
A menu will open with the option "Use a code or gift card".
Select this option, enter the 25-character code, and click Next to link the content to your account.
From a Microsoft account:

Redeem the code in your Microsoft account at https://redeem.microsoft.com . Click here for more information about activating a code on your Microsoft account.
After starting the game, select Skirmish or Multiplayer and select the United States to play Civilization.