If Rambox cannot access the camera and microphone and cannot screen share, it means that don't have permissions for those actions. Rambox should prompt for them, but if somehow this didn't happen, or the permissions were denied, you can manually set up access by following these steps.

1- In the top-left corner of the Mac Desktop, click Apple menu, then select System Preferences. 

2- The System Preferences window appears. Click the Security & Privacy icon.

3- The Security & Privacy window opens. Click the Privacy tab. 

4- In the lower left of the window, click the padlock icon to make changes. Enter your Mac's administrator username and password. 

5- Click the Camera section. Check the Rambox checkbox.

6- Click the Microphone section. Check the Rambox checkbox.

7- Click the Screen Recording section. Check the Rambox checkbox.

8- Close the Security & Privacy window.

9- Restart Rambox to enact these changes.