I'm pretty sure you need to extract the disk to an Amiga floppy disk instead. You have CrossDOS up and running, so I would do the following:
First mount PC0: so you can access the DMS file, and then copy the DMS file to RAM: disk (or harddrive if you prefer this instead). Then extract the DMS file to Amiga floppy using this line
DMS write (filename.dms)
This should do the trick, and hopefully you will have the setup disk you need.
You can see some specs of your bridgeboard a long with additional software
here. I hope it helps.