This is a common problem for Mac OS users. You need to check the screen sharing permissions for your browser. You can read more about screen sharing permissions in Mac OS on the following link: Turn Mac screen sharing on or off - Apple Support.
Additionally, it might be a problem for both Windows and Mac OS users who have pop-ups blocked in their browsers. You can read more on blocking and unblocking pop-ups in Google Chrome in the following link: Block or allow pop-ups in Chrome - Google Chrome Help.