While this is fine for upgrading the current computer, it is useless for creating a bootable USB drive. The createinstallmedia command requires the full package.
to prompt the "Get" button in your System Settings or Software Update. Terminal Command : If the App Store link fails, open Terminal and run: download macos catalina 10.15.7 full installer
A Python script from Greg Neagle’s “macadmins” tools can list and download genuine Apple installers, including 10.15.7: While this is fine for upgrading the current
If successful, the installer will download to your folder as Install macOS Catalina.app . This is rare, as Apple typically offers only the latest OS. If this fails, proceed to Method 2. including 10.15.7: If successful