https://support.apple.com/en-us/HT201372
Open Disk Utility and Format/Partition your USB key with a GPT partition table and Untitled as the name.
Then run the following commands in a Terminal:
Example for Sierra:
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sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia –volume /Volumes/Untitled –applicationpath /Applications/Install\ macOS\ Sierra.app
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Example for El Capitan:
[raw]sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia –volume /Volumes/Untitled –applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app
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Now you are ready to run Clover!
