Oliver's answer is still correct. You need to mount PC0 on your Amiga so it can read DOS floppies, which can also be read/written on your Mac. Format a DOS disk on a PC, put it in your Mac, copy the ADF file on to it along with transdisk from Aminet, put the floppy in your Amiga, and use transdisk to write the ADF to a disk.
--
moto