This is my first Linux system, and I'm on a Mac running OS X 10.10.5. I used these steps for downloading Ubuntu, but at Step 5 my USB was just not listed at all.
I also just tried using the Penguintosh software that was posted on several other questions, but I got a message saying that the application was "damaged and I should move it to the trash."
The Ubuntu I downloaded was Version 16.04, 64-bit, and the USB I'm using is a cheap 4GB Shintaro.
penguintosh
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