In order to Share Link directly to a user or an invited guest, you can easily do this by going to the Little Green Shield Icon, and click Copy Link.

If you copy this link and send it to someone, they can join you directly inside Zoom without having to register or pay for any lives that you've set up. This is how you can send a direct link to participants or speakers when your Zoom session has already started.

Consider setting up a group where you can share this for speakers to attend a particular time slot on your Zoom session.