Note: These steps may not apply for earlier versions prior to macOS Catalina 10.15.
There are additional steps macOS users may need to take to share their screen. To access your settings, by doing the following:
Click the Apple menu > System Preferences. Then, click the “Security & Privacy” icon.
Under the “Privacy” tab, you’ll find a “Screen Recording” option. Please ensure the checkbox next to your browser's name is selected.