I don't know for certain, but I expect that the resort's package handling policy would apply to groceries:
This could add up quickly - hopefully they would only consider your grocery order to be one package even if in more than one box.
If you are only getting a few essentials, perhaps ordering a grocery prestock from the Marketplace would be a better option? Prices are higher than Publix by a good bit, but the convenience is great.
https://owner.vistana.com/services/genstore_categories.jsp?propertyId=01&shoppingTypeId=1 Note that there are fees associated with the prestock service as well, so you would need to weigh it out carefully.