The WHDLoad thing:
ADF files are mostly from cracked ones. So using them for WHDLoad is not a good idea, because it won't work. ie: WHDLoad will quit and tell you it's either a cracked version or unsupported. :-(
This counts to nearly all NDOS games. (NDOS=NonDOS... or explained as a system which basically closes down DOS and uses it's own hardcoded system functions)
These are disks where you don't get any files too see or the disk will show up as DF0:NDOS on your Workbench.
But many DOS games (DOS games uses normal files on the disks and system functions to run the game) can be installed with WHDLoad. JOTD mostly supports in all in his installs cracked ones too. So you can install these ADF games. If you're using WinUAE, then put the ADF image into drive 0 when installing.
If you're using a real amiga, then you have to write back the ADF file back to a real floppy disk, or use a virtual disk system like FMS (which i use always). :-)