You are commander of the Black Talons company, currently stationed in the Oberon system. After an eventful campaign, the military Tzanar Union has overrun the planet of Genai and blocked all departure from the system: leaving you and the Black Talons stranded.
Open the Steam client, login and locate the Games tab on the top menu. Click this and then select “Activate a Product on Steam…”
Enter your unique code that's displayed on the 'Orders' page of CDKeys.com and follow the prompts to activate.
Your game is now viewable in the “Library” tab and is available to download/install when you’re ready. You can find additional support for the Steam client here: https://help.steampowered.com/en/wizard/HelpWithSteam