I have been following the exact steps as outlined in this tutorial video, with no oddities happening along the way: https://youtu.be/twQbHWJF7LA
Well, I was able to follow it up and until we got to the Partitioning part, where he says to load DOS up in the machine, presumably meaning the PC-10 in this case.
The PC-10 loads the ISA IDE to SD Adapter just fine, it even tried to look for Drive C (The SD Card) for like 10-15 seconds, until giving up then and there (as seen in the pic).
(ISA IDE to SD card Adapter i got:) 
In other words it seems that the Adapter either doesn’t recognise what is on the Card and I’ve done something wrong in burning the provided image onto it or formating, or it doesn’t recognise the card itself to begin with. Its a Brand new 32GB SanDisk SD so that be pretty suprising…
In other words… im out of ideas… i tried different DIP switch configurations and all, but no change. Perhaps the PC-10 III Simply doesnt like the Adapter… or can’t run 6.22… im just out of ideas and frustrated. I’ve had this thing for over a month now with no luck in seeing it run once properly, and original 5,25" DOS Bootdisks are expensive and take a while to arrive. Should I just bite the bullet and go for one? I don’t know. Any advice is much appreciated…
Have you tried a smaller card? 32GB was pretty well unheard of, even in the DOS 6.22 days.
It’s been a very long time since I’ve thought about stuff like this. It reminds me of when I was trying to get a 1GB drive working on a 486 when I was in college. The drive wasn’t seen (just like you’re seeing). What I had to do was install the manufacturer’s backwards compatibility software (it was for systems that were too old to have BIOSes that recognized drives that big) so that the BIOS, when it probed the hard drive would somehow load a TSR that added support for large hard drives.
Looking up the card in question, it loads the XTIDE BIOS, and the card has “Select XT-CF(PIO) Mode/Base IO 300h” silkscreened on the back. Zooming in on the front of the card, it doesn’t look like you can set that on the DIP switch block for some reason. I don’t see any documentation for download from the site. Did any docs come with the card?
No there wasn’t any documentation that was delivered with it sadly. Though seeing that in the tutorial it showed much of the same text on Boot up, i think its safe to asume the card itself works fine. Someone else in the thread mentioned that it might not work because its an HC SD card, which probably can’t be read by the adapter, so tomorrow im buying a normal SD card to try it tho