Download Macos Catalina | 10.15.7 Full Installer |best|

Once you have the file in your Applications folder, you can create a bootable drive with a 16GB USB stick: Plug in your USB and rename it MyVolume .

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while holding down the Option (⌥) key immediately after you hear the startup chime. download macos catalina 10.15.7 full installer

when prompted (you won't see characters as you type). Once you have the file in your Applications