You can download a list of all registered participants via CSV for any given event in the Event Registration plugin. This can be particularly useful for following up on mandatory trainings or even sending a thank you message or follow up materials to people involved in a specific event.

1. In the Studio, navigate to Content > Event Registration.
2. Navigate to the event for which you want to export the participant list. 
3. Click on the event to open the detail view. 
4. Click the three dots to open the actions menu.
5. Click Export Participants.