Always use LPD for any Fiery based print
Never look to the printer manufacturer for drivers either, always go to the source (EFI)
In the case of the C70 there have been 10.15 drivers for quite a long time, to get them:
Take the IP of the Fiery (Go to Services Home on the copier, select the Fiery logo on screen, when it loads, copy down the IP address by the EFI logo at the lower right)
Open Safari/Chrome and put the IP in the Addressbar to load Fiery Webtools.
Select the Configure tab and then Check For Product Updates
Select the Print Drivers tab and find the latest dated Mac driver (They are utterly randomly ordered instead of by date)
Oh wait, so I was playing around with the printer settings and I was able to get it working by using the LPD (Line Printer Daemon) instead of IPP (Internet Printing Protocol). I would try that using the same drivers you download for the C60.
We are also having the exact same issue. We downloaded the latest driver from Xerox but the issue persists and it is stuck in ready to print.
After updating to MacOS Catalina, I can no longer print to my Xerox Color C60 EX-i Color Server. I noticed that there is no driver listed for that device so I installed the Common Printer Driver and then selected my printer from the Printer Software (Xerox Color C60, 5.3.0). I was able to connect to the printer and it successfully set up the printer and showed the correct icon and get green.
However, when I try to print a test page, it tries to print and then pauses to say "Ready to print" and the printer status changes to Paused. On another Macbook running Mojave, we are still able to print no issue. It seems like the issue is the OS, so how can I fix this?