Use this to update from an earlier version of Catalina (10.15.x). macOS Catalina 10.15.7 Update (Official Apple) Standard update for 10.15.6. How to Create a DMG/Installer from the App Store App If you need a file for a bootable drive but only have the file from the App Store, you can create it: Download the Install macOS Catalina.app Mac App Store Disk Utility File > New Image > Image from Folder
Downloading from Apple ensures the DMG or installer hasn't been injected with malware or "cracked" versions of system files. Why Avoid Third-Party "Free" Downloads? mac os catalina 1015 7 dmg download free
Only download macOS from Apple directly or via the Mac App Store. Use this to update from an earlier version of Catalina (10