After I posed the question I found the terms and conditions. See below.
21. If the Guest wins an Upgrade to an "Aurea" or "Yacht Club" experience cabin, the original booked experience "Bella" or "Fantastica" will be changed with the new experience "Aurea" or "Yacht Club". The new experience will guarantee to Guests all the benefits related to the "Aurea" or "Yacht Club" experience.
https://upg.plusgrade.com/terms/partner/9Ck2Ks4MSC?lang=en