I think your options are limited. Xerox has given up on this device for macOS, and you need xerox support to drive the non-printing MFP functionality. It is too old to receive Apple's AirPrint support which would solve the printing/scanning issues. I may be wrong, but I believe that you require compatible xerox phaser 6180MPF drivers installed on your Mac in order to submit print jobs to this device connected to a Windows box. The other MFP functions would be done on Windows. Xerox continues (in 2019) to provide Windows 10 x64 device support for this phaser device (what a surprise).
If you had this device working on Mojave, and you performed a Time Machine backup of Mojave prior to the Catalina upgrade, then you can boot into Recovery, and select Restore from Time Machine Backup to wipe the Catalina drive, and repave it with Mojave, applications, and your data as they existed prior to the upgrade.
There have been no xerox drivers provided for the 6180mfp since El Capitan (10.11) in 2015. It is supported in the free, source-forge, GutenPrint v5.3.3 for Mac, but there is a standing Catalina compatibility issue with this release of GutenPrint that has not been resolved, and with uncertainty whether it will work with Catalina. There is an install at your own risk caveat on the site.
The postscript PPD for this device is available for Linux/UNIX but only will enable printing features, while the scanning and/or faxing will require compatible xerox drivers. I believe there is only Postscript or PCL printer driver support for this device on Linux.