Yeppers, AIAB needs an ADF of the Workbench 3.0/3.1 disk. So AIAB is not a free Workbench. It just has needed and presetted files of shareware and freeware tools (like MUI etc). AIAB has no copyrighted Amiga files in it. :-)
So you still need to get a hold of the original Workbench disks :-)
Getting them to ADF on Amiga is easy, just create a diskimage with a tool like TransADF, Image2Disk etc, then compress (preferably zip) your image and copy it onto a PC formatted (720kb) disk. Then take that disk to your PC and get that file. Easy :-D
There are lot of other ways to do that, just try and find out. Amigans always use their brain :-D