Is Adobe Connect free to use, if it is used only to participate in meetings?

Yes. Whether as a participant or even if promoted to Presenter or Host, Adobe Connect meetings can allow anyone with the URL to join at no cost to the participant.

Adobe Connect Meetings allow participants to join in the browser with no downloads, or through the free desktop or mobile apps.

Need to create and Host meetings? That's when licenses are purchased and I can provide information about licensing options.