I have successfully created the General user-managed app and also using node.js and express i can connect the zoom account with my app and book the meetings of that specific user .
But the issue is i only can able to connect the user which created that app in market place or lets say admin i could not able to connect any other account to my app.Also the option to add users to test the app in development phase . The search results does not show already created zoom user to add in the app .
Reference :- General user-managed-app , Development mode , zoom apis ,