I wish it were that simple, it just doesn't show up on my 2011 i5 quad-core iMac at all. I've tried every variable of turning it on whilst plugged in or not, turning it on after it's plugged in, etc... & it never shows for me. I still need to take the SD card out to transfer anything from it.
I have ordered a USB-C (3.1) to USB-3 (3.0) plug & a male to male USB 2.0 cable, to see if that will work, as someone has mentioned it working for them with their older computer that doesn't have any USB 3.0 or 3.1 slots. Fingers crossed.