Hi,
Great find. One of the best benchtop mills around but rare... i wish they still make them!
I believe you are missing the CNC control unit (Cortini CNC 2437), without it you will need something like Mach3 to run programs and the steppers.
Generally the Zebotronics stepper drives can be wired for other controllers (you can still find info on the internet about Zebotronics Stepper Drives) but you will need a modern breakout board unless you really good in electonic PCB.
I do have some electrical diagrams for the L300.
Regards
Marco