Defender for Cloud Apps send cloud discovery data from Microsoft Defender for Endpoint to Microsoft Defender for Cloud Apps via Windows devices (Windows 10 and above). Note although we currently don't Discover MacOS traffic coming from Defender for Endpoint, we are able to block/warn on MacOS devices. We've heard a lot of feedback around the need for discovery on MacOS devices via Microsoft Defender for Endpoint. It is high on our list and and is something we are actively looking into. Stay tuned for updates on this!