Thanks for reaching out to the Zoom Developer Forum, I am happy to help here!
As seen in the documentation, for the Get past meeting participants endpoint
You can access this endpoint both with a user level app or an account level app so, to answer your first question yes, you can use this API with an user level app and call this endpoint with it and you do not need to subscribe to any events/webhooks to be able to call this API. You could potentially subscribe to a meeting.ended webhook to know when the meeting is over so you can go ahead and call the endpoint.
For your second question, the user who installs the app will have to meet those prerequisites, cause your app will basically be making API calls on their behalf and those prerequisites are neede.
hope this helps,
Elisa