Make sure to save the samples from your Mac in .wav format and the AKAI should read the disk fine.
ahhh. if were only that easy...
unlike the mpc series of samplers, the s series (until the 5000) could not natively read .wav or .aiff files.
so you can't simply import samples from the computer.
nor will the akai read a mac or pc formatted disk...nor will a pc or mac read an akai formatted disk...expect in a very low level way.
you can use the program akaidisk on pre-xp windows pcs. this enables you to transfer samples to the disk using a low level protocol, thus not requiring the pc to really recognize the types of files that are being dealt with, or the base formatting of the disk.
there is also a program called mesa that you can use on pre-osx macs. this requires a scsi and midi connection. for windows pc computers, you can use a program called millenium, along with a midi and scsi connection.
or you can just run audio cables to the akai, and resample. for single hits (drums) or short loops, this is often the fastest.
the workflow that many people have gotten used to, in terms of auditioning, dragging, and dropping samples is far different than working with these older samplers. that said, they are robust, good sounding, and very stable machines that will serve you well!