If a client does not respond to you after you have given them a reply over the messenger service, don’t stress about it. There isn’t much you can do other than make the occasional probing question to them.
Clients are the people on the tight schedules, not you. So when a client doesn’t respond to you, it could mean that they’ve found another Talent or that they can’t answer right away.

Either way, it’s out of your control, so don’t stress about it