I have looked at your link but I was not able to find the document that describes the control interface and provides the list of commands it understands.
I seem to understand that it use CANopen DS402.
I don't know stepper motors, so I'm not sure if that interface is for "programming" motor or if it's for control it.
Basically you'll need to research CANopen and other Arduino projects that have used it and
see where you get - there are some matches on the forum for CANopen.