Provided that it is an internal IDE Zip, for the A1200 you need an adapter cable (2.5" -> 3.5") and an ATAPI driver, for example IDEfix97.
For the A500 you need a controller first.
Parallel port ZIP drives do not work on the Amiga.
However, you can create an adapter to connect to the parallel port and the joystick port and with the special software it should work. Instructions can be found on Aminet.
Bye,
Thomas