Activate with Steam:

Download and install the Steam client on your PC. ( https://store.steampowered.com/about/ ), then sign up and log in.

Locate the Steam key in your cdkeys.com confirmation email, and copy it to your clipboard by pressing “Ctrl+C”.

Open the Steam client and locate the “+ ADD A GAME...” button on the bottom left of the window. Click this and choose the “Activate a Product on Steam…” option.

Paste the key from your clipboard in the “Product Code” section when asked, and follow the rest of the prompts to add the game to your library.