Arduino Uno unable to detect serial port on MAC os Mojave 10.14.2
If you are using a genuino or genuine Arduino, the most common cause of this is using a USB power only cable to connect rather than a data cable. (You only need the CH34x_Install_V1.4.pkg if you are running an Arduino clone based on that chipset)

If I ran the world, the USB standard would include some way to distinguish whether it's power only or power and data without having to test it with a multimeter. I know, I know, that's crazy talk.