Through your settings, you can control if the Join From Browser link appears automatically or if it only appears once the participants attempt to download the Zoom client.
By default, participants joining through the web client do not need to be signed in to a Zoom account, but the host can require authentication. The web client can help users who are limited in what they can install or download, allowing them to use their web browser and join Zoom meetings without downloading the application. The Zoom web client allows joining a Zoom meeting or webinar in a web browser without downloading any plugins or software.