Am trying to boot my new Air from the clone of my previous MB, have enable lowest security and booting from external devices in Recovery mode, but I get the message that the system needs to be reinstalled on the startup disk, but when I try to that it just boots back up into the AIr. I have done this process for decades, cloning my old computer to the new one with no problems. I don't want Catalina, and so am trying to clone the Mojave (latest version) external to the Air.