Hello Marina!
Welcome to planDisney! You mentioned two of my favorite places in your question: Costco and Walt Disney World Resort. One provides me with delicious croissants and soft pants while the other fills my yearly magic and Mickey Mouse hugs quota.
You can be able to link your package to your
My Disney Experience Account. Costco should have sent you an email with a confirmation number and if you purchased a package with a stay at a Walt Disney World Resort Hotel or just tickets you can
link them to your account here. The confirmation number could be a series of letters and numbers. If you continue to have issues with entering the confirmation number then call the lovely Cast Members at
Disney Resort Hotel Reservations. If you have not received a confirmation number then please reach out to Costco Travel to get that fixed! I highly recommend you connect your reservation to your account as soon as possible as it is a very important step in your planning.
By setting up your My Disney Experience Account with your tickets and package details you can begin
checking into your Resort room even now! Then, when you arrive you can get a text or notification in your My Disney Experience Mobile App when your room is ready. I have had great success in the past few years with my room being ready as soon as I get off my flight. It's not guaranteed but it has been successful for me quite a bit. I love just heading right to my room, dropping off my luggage, and jumping right into the magic. Another major reason to have your account set up is so that you can make
dining reservations and even secure a spot on a
Virtual Queue to enjoy special attractions!
I hope this helps and you have a magical time!
Happy Planning!
-Nimmy