Thought I should update this post for future reference
I noticed the default settings on my BIOS had SATA operations configured as "RAID On"
The moment I changed to that to AHCI, I was able to get through the installer and everything else in the documentation
It took me a while to realise any edit I made when "rotated" was going to a totally different folder in attract. So after a few hours on it, I managed to get demul to work for the few vertical shmup on naomi. Also struggled with the copying of roms - every time I used the copy roms/videos from the ui
https://i.imgur.com/qc7FLf6.mp4
I love how I can set it to read only and how windows is pretty much hidden, down to the mouse cursor (one of the things I disliked with demul was the cursor that always appeared when I launched a game, even though I had no cursor - maybe it was me who didn't know how to get rid of it).
The hardest part I'm having with this build now is when it comes to modifying anything, I either have to turn the windows settings back on or unplug the hdd and make the necessary edits (only edits I'm making is in attract and moving files around)
Once again, thanks Chunksin for providing this for everyone. I'm now going to do the same for a horizontal build and am currently trying to work out how to configure the "cpu" settings in mame as I'm reading a bit about CPU and Blitter settings for CV1K games (I found blitter settings,
but can't find CPU)
Edit: found the CPU setting by changing the "cheat" parameter of the mame.ini from 0 to 1 under the # CORE MISC OPTIONS section. Once I did this, I could see it in the slider settings.