Enable Screen Sharing Permission on Firefox

To enable screen sharing on your Firefox browser click on the Permissions icon next to your URL bar. Make sure that the permissions for Screen sharing are not blocked. Choose to share your Entire Screen and click Allow. Once you allow permissions, refresh your browser.

If you're using a Mac, a popup will appear asking to enable screen sharing on Firefox. Open System Preferences and check Firefox in the list to allow screen sharing. First, you might need to open the Lock icon before making changes.

Here's how to enable screen sharing on Google Chrome using MacOS. 

If you don't see the screen-sharing icon in your URL bar, click on the padlock icon > connection secure > more information.

Here, find Share the screen and click Always Ask or Allow. Refresh your browser.