If you are using Windows, you must close VirtualBox and run a VirtualBox macOS Unlocker script via Command Prompt to allow macOS to boot on non-Apple hardware.
hdiutil detach /volumes/Install\ macOS\ Catalina
Since Apple doesn't provide official ISO files, you'll need to create one from the installer you downloaded. Here's how: Download Macos Catalina 10.15.7 Iso File --39-LINK--39-
hdiutil attach /tmp/Catalina.dmg -noverify -mountpoint /Volumes/Catalina Use code with caution. Step 4: Write the Installer Files to the Volume
# Verify codesign codesign -dv --verbose=4 /Applications/Install\ macOS\ Catalina.app If you are using Windows, you must close
Download macOS Catalina 10.15.7 ISO File: Ultimate Installation Guide
Convert the dmg to iso: hdiutil convert /tmp/Catalina.dmg -format UDTO -o /tmp/Catalina.cdr If you are using Windows
Create a blank disk image: