Since Apple does not provide a direct ISO or DMG link, you must manually create one from the installer app you just downloaded. Apple Support Community To Create a DMG Disk Utility
: Click "Get" to begin the download. This will save a file named "Install macOS Catalina.app" to your Applications folder. download macos catalina 10.15 iso and dmg image
The safest way to obtain the necessary files is to download the installer directly from Apple. This ensures you are using authentic, malware-free software. Microsoft Community Hub Open the App Store official macOS Catalina link provided by Apple Support to launch the Mac App Store. Download the Installer Since Apple does not provide a direct ISO