I tried just creating the meeting, but got error ""code": 1001, "message": "User does not exist:.""

Thanks for the clarification @gumax1962

So, it looks like you want to create an OAuth app:

And again, in order to have 3rd party users authorizing your app, it needs to be published in the Marketplace, here is a link to our Docs:

Let me know if there is anything else I could do for you.
Best,
Elisa