You have to register it within 14 days of the invoice date, which is obviously impossible for most preorders. If you've missed that you'll need to buy an extended warranty to make it eligible for Step Up.
 
(Note, there may be some other reason why your specific purchase isn't eligible, so you may want to rule that out before spending more money)

RockmanBN
I preordered a 3080 XC3 through the retailer called Adorama in September. Just got my card this week and uploaded my order invoice. I checked my product information and it says that it is not able to Step Up? Are 3080 XC3s not able to Step Up to 3080 FTW3's? I know the wait is going to be very long.

To be honest, I wouldn't even bother with that "upgrade" because it won't really be an upgrade. Literally no point in stepping up a 3080 XC3 to the FTW3 as the performance difference between them will be 1-2% at best. Since you obviously missed the 14 day after order window for free step up option now you also have to buy the extended warranty on top of paying for shipping both ways for your card + the difference in cost between the models.