1. Go to this website https://profile.callofduty.com/dayzero and create an account or login.
2. Connect your PSN, XBOX or steam account.
3. Press the "Please click here if you are entitled to this content and did not receive it." button.
It will say "Your weapons and exoskeleton will be activated in your account within the next 24 hours.
PLEASE NOTE: You will need to restart the game in order for the in-game content to appear."