@Reeselh07 It doesn't matter that you downloaded Supernatural on a different computer. What does matter is if you never registered it, or you registered it to a different account. In the first case, as long as you still have the code for the pack, you can add it to your account now. In the second case, you'd need to contact EA customer support and ask that the account with Supernatural on it be merged with your main one.
https://help.ea.com/en/contact-us/
You can also contact support if you're not sure what happened to the pack or its code, but you'll need to be able to demonstrate ownership in some way. For example, show the pack in your Origin purchase history, or take a picture of the disc, case, and insert with the code printed on the back. You can upload these images directly to a live chat session.