They tend to release it for free after 6 months or so. If you didn't preorder.
Message Amazon suppourt asking where it is.
Sounds like you got scammed or read it wrong, there's a different Curator's Cut code for each game, all of which are eventually released to everyone for free. I'd just wait and message the sell on ebay/check the listing see if you read it wrong, if they did message them or eBay.