Camp Dolphin is still open: https://swandolphin.com/activities/kids/camp-dolphin/
I don’t know if the freebie is still offered.
Hmm... I wasn't aware that site is old. WDW still mentions Camp Dolphin, though it could be outdated.
However this page is accepting reservations and the copyright at the bottom is "© 2023 Marriott International, Inc. All rights reserved. Marriott Proprietary Information"
https://swandolphin.247activities.com/
Wow, that's disappointing they've apparently intentionally left that info out there. I went almost all the way through the registration. I've never been a Marriott fan.