Every meeting has a lobby available. When you first start the meeting, let all your interviewers join about 10-15 minutes before the first interviewer is scheduled to arrive and then lock the meeting. The next person that joins will wait in the lobby until the host lets them in. When the interviewee leaves the meeting or is expelled/moved to the lobby by the host, the next interviewee can be admitted.
If you need them to be able to see persistent chat, you would need to use Webex Teams (now just Webex) to host the meeting and use the Webex Space for the chat. It will be immediately viewable by everyone in that space though and everyone will need to have a Webex account. Either from your organization or a free account they can create.
