Step 1: You will need to download and install Uplay if you do not already have it: https://uplay.ubisoft.com/en-US
Step 2: Once it’s downloaded, run the application and select a directory to install Uplay in. If you don’t already have an account, you will be required to create one.
Step 3: Click the top left 3 bar menu button, select Activate a key. A product activation box will pop up, type or paste in the activation code.
Step 4: Success! Your game will be activated and bound to your Uplay account. The game has now been added to your Uplay library where you can start the download.