stk500_recv() error on macOS Sierra, Arduino UNO

I followed the instructions on the starting manual for macOS, so I selected:
Tools>Board>Arduino/Genuino uno
Tools>Port>/dev/cu.usbmodem14341 (Arduino/Genuino uno)

The screen capture is what it shows up on my Arduino IDE.

From what I have found online, people seem to relate the stk_500_recv() error with not installing external drives, but Arduino UNO does not need external drives, so I don’t see what the issue is here.