With the Disney Rewards account you get a credit card with the dollars on it.
What I had to do pre-pandemic is give a regular CC first, then go to guest services and then give them any gift cards and the Disney Rewards card. When I checked-in at the pier they wouldn't accept the gift cards and rewards card. That had to be done at guest services. When I got to guest services I then told them to prioritize the gift cards/rewards card over the regular credit card.
This is my plan for my upcoming cruise. I added the regular CC to my advanced booking and then I will go to guest services and add the gift cards and rewards card when on board.
You have all week to do this, since your regular CC gets charged at the end.
Don't lose any gift card or rewards card since the $ will go back on if you don't use it all.