I don't think that's a Mac issue. Or a Connect issue. That's an issue of your Mac user talking into a microphone while speakers are feeding the same audio back to her while she's speaking. Then it gets heard by the microphone, and plays through the speakers again. And again. And again. It's a continuous loop. Until either the speakers or the microphone gets turned off.
Your Mac user needs to not be broadcasting any sound but her speaking voice. If she can hear her speakers, you can bet her microphone does. And those speakers are reproducing her voice at least as loudly as you're hearing it. I can't emphasize this enough. That is the root of her — and your — problem.
If she doesn't want a headset, a set of wired earbuds with a microphone, like you'd use for your phone, plugged into the audio jack, is the solution. If you keep using a separate microphone and speakers, you're going to keep getting the same unfortunate results.
Hope this helps,
Randy