That's exactly right. All devices needed a device driver to communicate. Console, Floppy, and some combination of serial or parallel printer were fairly standard. Profile drivers were pretty common too. You can use the System Config Program on the Utilities disk to move drivers onto and off of the boot diskette.
It's basically the same server as the 2000's era DOS ADT server, except it knows how to control Mac serial ports under Classic Mac OS. Nothing fancy; it can only transfer 5.25" .dsk images. But of course that's all you need for the III. You can download the MacADT program from the ADTPro download site, under dos-adt. It's buried within that package as MacADT.sit.