Thanks for the post, and thanks for providing the information. The code snippet looks good, and the return value 0 means the meeting is on but just the view is not showing up. Are you using SceneDelegate or just AppDelegate?
Regarding the group ID, that group ID is only included in the demo app’s entitlement:https://github.com/zoom/zoom-sdk-ios/search?q=group.us.zoom&unscoped_q=group.us.zoom, if you are using screen share, you might need to follow the instruction here to configure the screen sharing feature: https://marketplace.zoom.us/docs/sdk/native-sdks/iOS/mastering-zoom-sdk/in-meeting-function/zoom-meeting-ui/screen-share, if you are not using screen share, you may just remove the screen share framework and the extension from your project.
Hope this helps. Thanks!