The Iomega ZIP drive is not supported on 10.11.3. It really has been far far past end of life for several years.
The only way that I know of to get it to work on a Mac is to backload the entire operating system. The drivers and support software for that drive do not exist on El Capitan.
I truly wish that I had better information for you, but unfortunately there is simply no real, supported way to do this. The closest way to get what you want is to use a USB version of the ZIP drive, but you are still in maybe/maybe not territory due to the age of the drive.
Please let me know if I have misunderstood or if there is anything else that I can do for you.