This is very similar to the unsigned driver issue in Windows 8.
On newer versions of OS X, when you double-click the install packages inside the FTDI disk image, you may be presented with a very Windows-esque type error about not being able to open the files because they are not from an identified developers. Troubleshooting: Unidentified Developer Error Browse the Hardware > USB tree to determine what COM port the FTDI enumerated on. This is similar to the device manager used on Windows OS. You can determine what COM port an FTDI device enumerated to by opening the Mac OS X's 'System Information' in Lion or later (or 'System Profiler' in Snow Leopard and earlier versions of Mac OS). Plug it back in, and select the device that has now reappeared. The device you unplugged should no longer be listed. However, there are times when we need to use Windows OS for tasks that cannot be completed with macOS, like using Windows-only software and playing PC games. To figure out which device is which, look under the Arduino IDE's 'Serial Port' menu. Note: If you have more than one FTDI device plugged in to your computer at the same time, all of the devices will show up in the Arduino IDE's Serial Port menu and device manager.
