There is a very very difficult guide to follow up on here from 2016 and I thought I would just add this as the solution required a LOT more research than I liked.
Many thanks to the guide and forcing me to learn a lot of info I was interested in regardless how stupid I wanted to be and fudge a quick solution.
Step 1 - Mount EXFAT Drive w/ OMV.
Step 2 - Install 'exfat-fuse' via debian commands
Step 3 - Run debian command 'nano /etc/fstab/' and change
'/dev/disk/by-uuid/D82B-3942 /srv/dev-disk-by-uuid-D82B-4952 exfat defaults,nofail 0 2'
into to
'/dev/disk/by-uuid/D82B-3942 /srv/dev-disk-by-uuid-D82B-4952 exfat-fuse defaults,uid=0,gid=100, 0 0'
it's just that easy. (jk it is riddled with un-mentioned caveats but this should keep it after rebooting until you change setting in omv again)
time to write to some smb shares.