How can I retrieve past meeting registrations?

Hello @HenryII ,

You can check if you are able to get the registration report via the Reports admin section on the Zoom Portal as described in How to generate reports after the meeting.
However since the meetings are no longer displayed under the Previous Meetings page, these indicates the Meeting ID already expired and the Registration reports are also no longer available (as mentioning in the Notes section of the article linked in previous phrase).

Hope this helps.
Cheers.