Use Catalina 10.15.7 primarily for:
Running lightweight, low-overhead testing environments inside virtual machines. Download Macos Catalina 10.15.7 Dmg File
This is Apple’s security expiration. Solution: Use Catalina 10
Set the Format to and the Scheme to GUID Partition Map . Name the drive Untitled . Click Erase . Open Terminal and input the following command: Security & Privacy >
softwareupdate --fetch-full-installer --full-installer-version 10.15.7 Use code with caution.
Then go to System Preferences > Security & Privacy > General and select "Anywhere".