We stayed at Pop a month ago, and I did the Staples water thing.... worked out great. I ordered on the Wednesday before the Monday we arrived. When I checked in, I just told the CM that I should have an order from Staples-- she checked the computer, and said, yes, it's here.
She asked if I would like it delivered to the room. If I remember right, it was delivered an hour, or so, later-- but NOT by Magical Express... I think they delivered luggage a bit later, but I know it was a separate delivery.
I put my resort reservation number on the order form (online.) I think I just typed it in after my last name on the same blank-- there was no separate blank to type the res. number, but it came out fine.... on the printed invoice on the outside of the cases of water it just looked like: "Firstname Lastname Res. # XXXXXXXXX."
I did not call ahead to check anything with Pop. Just took my chances!!!
I did use the $5 coupon code that was sent to me when I signed up for Staples Rewards. It expired fairly quickly (at the end of June-- I signed up in June) so, assuming this is something Staples always does, I wouldn't sign up until closer to my trip, if I were you.
My total for 2 cases of Nestle water (48 bottles) was $14.xx. I've read that you can call Staples, and have them take off the shipping charges, but I never did. I was pretty thrilled at the price of less than 30 cents/ bottle, and was overwhelmed by everything else I had going on at that time, so I never even thought about it.
HS