Hey Julie,
We have a plugin called Community Tickets that would allow most of what you describe here. It does not use the specific “Adaptive Payments” API from PayPal, but it does let people submit events and collect their own commission on the ticket sales of that event.
Then, in your Community Tickets settings, you can just to choose to not collect any fees on top of these sales. This would effectively mean that the event submitter collects 100% of the ticket earnings:

Community Tickets is one of our most expensive add-ons, so I’m sorry to bear that news, but if you’re interested in using it, all of the following plugins are required to be installed and activated on your site:
• WooCommerce [free] – EDD is not fully supported at this time, unfortunately!
• The Events Calendar [free]
• Event Tickets [free]
• Event Tickets Plus [$89/year and up]
• The Events Calendar: Community Events [$89/year and up]
• The Events Calendar: Community Tickets [$149/year and up]
Let me know if this information is helpful!
Cheers,
George