You have a Microsoft 365 E5 subscription that contains 500 macOS devices enrolled in Microsoft...

To apply Microsoft Defender for Endpoint antivirus policies to the macOS devices, you need to install Defender for Endpoint on the devices. You can use Intune to deploy a script that installs Defender for Endpoint on macOS devices. After installation, you can use Intune to create and assign antivirus policies to the devices. References: https://docs.microsoft.com/en-us/windows/security/threat-protection/microsoft-defender-atp/mac-install-with-intune