If you are looking for the file, you are likely trying to revive an older Mac, perform a clean install, or set up a virtual machine. Catalina was a landmark release as it was the first macOS to drop 32-bit app support and introduce Sidecar .
If you specifically need a .dmg file for a virtual machine (like VMware or VirtualBox) or for archiving, you can convert the installer app using : macOS Catalina dmg file download for old macbook pro macos catalina 10.15.7 download dmg
: Visit the Official macOS Catalina Download Page using Safari. If you are looking for the file, you