The issue was the GX420d would not print. I followed her instructions and with a little guess which out of four models listed would work I chose ZPL. It prints the shipping label correctly but is only 2 11/16" x 3 15/16" and should be about 4" x 6". I will send her an email on how to enlarge the print out.
If anything was going to prevent an office switching to Z16 Pro it was the Zebra printer. I am delighted it looks like the switch will be coming sooner than expected. WoW
Opened up the printer settings and changed the size to 4x6 works perfectly