Dear valued Unreal Engine user,
You should be able to redeem market place codes in the account settings on the Unreal Engine website:
https://www.unrealengine.com/account/code-redemption
You do need to log in with your epic games account and after you have redeemed it, you should be able to download from the Library tab in the Unreal Engine section of the Epic Games Launcher.
Also, just in case this is a single use code and not for the course, you probably would not want to share the code, here and it may be a good idea to edit the title, and question to remove the code itself.
Thank you for your continued support,