Here is the version I am running of SiLabsUSBDriver
CP210x Macintosh OS X VCP Driver v5 Release Notes
Copyright (C) 2017-2018 Silicon Laboratories Inc.
I have just reinstalled do to a hard drive failure on the Mac mini and have it back up and running.
Make sure to close the other connections (/dev/cu.Bluetooth-Incoming-Port) and then open the /dev/cu.SLAB)USBtoUART port
I am running the same Vantage Pro 2 with great success on a Mac mini 2011 with macOS High Sierra 10.13.6