Be advised the following method is a workaround and is not endorsed or supported in any way by Xerox, there is no driver fo r10.11 as of todays date and I don't know of an ETA, so the official response is now "Our developers are currently developing / testing a new driver keep checking Xerox.com for a 10.11 driver, thank you and have a nice day."
Unofficially, to get to printing stuff today, try the following:
So, The new security stuff added killed the ability to install some drivers due to System Integrity Protection (SIP), aka “rootless” mode
Really, the same sort of thing MS does where if the driver is not digitally signed it doesn’t get installed. (Win 10 , Server 2008-2012)
Turns out, you can disable it, and it is pretty similar to how it is done in MS OS’s.
So now the Mac is back to normal locked down mode, driver/software should still work.