Am I guaranteed an offer if I add it to the list?

No you're not. All of our offers are limited and in some cases may run out in a very short time. You are only guaranteed the offer once you have uploaded your receipt with the correct item (provided the offer still exists). If the automatic scanner misses the item, you can add the offer manually instead. If the receipt goes to manual review and the offer was included in the upload, we will approve it within 72 hours unless the weekend gets in the way.