If you are already on an older version like Mojave, go to System Preferences > Software Update to find the upgrade option. 3. Creating a DMG or Bootable USB
Apple distributes the OS as a .app file. To turn this into a .dmg for use in virtual machines or external drives, follow these steps: macos catalina 10.15.7 download dmg
If your Mac is compatible, you can download the full installer directly from the Mac App Store If you are already on an older version
hdiutil create -o ~/Desktop/CatalinaInstaller.dmg -srcfolder /Applications/Install\ macOS\ Catalina.app macos catalina 10.15.7 download dmg
Once finished, unmount the volume and move the resulting DMG from your /tmp/ folder to your Desktop. Important Compatibility Notes