The problem is that Zebra printers do not use a "font" for printing barcodes. Instead, the barcode printing is all built into the printer. Your software simply sends a command to the printer that says "print barcode type x size y at position z" and the printer does all the hard work. The barcode has to be printed so the bars are in vertical position, or problems may occur.
The latest Zebra drivers and firmware date from 2014, so are not being updated any more.
You might have better luck with the Zebra Windows Printer Drivers by Seagull which date from this year and are being updated regularly. The Seagull website also contains much information which can be useful.
See also Resolving Print Quality Issues, just in case this might help.