Here is the Quick Start guide regarding how to run video calling samples:
Please make sure that you have a QuickBlox account or create a new one: QuickBlox Admin Panel
Android SDK - Advanced | Video Calling | Android SDK | QuickBlox
Please note that the implementation of screen sharing functionality is up to the client side for React Native and Flutter.
Feel free to check our official documentation for more information that will help you to integrate QuickBlox services into your applications / projects or contact our Support team by submitting a ticket if you have any other questions.