I realize that it has been over 3 years since the original question was posted but I'll reply in case it helps people in the future. What I did for my 2 cameras was partition a 2TB hard drive into 2 1TB NTFS partitions, one for each canera. I did this in windows.
Then in Unraid I used the unassigned devices plugin to create an SMB share for each of these partitions and created a user "cameras" that is only allowed access to this share. I then I logged into the cameras and entered the folder path and login in the net drive settings. Make sure you change NFS to SMB.
I did have to enable NetBIOS (and possibly WDS, I have it enabled but I'm not sure if this is why) in SMB settings.
My cameras have been recording flawlessly for about a month now.