Its very strange that the aforementioned config (pciHole.start/end) setting seems to be required for some but not all. I wonder what the determination is? I know for my setup, your steps worked perfectly and I've read others having success without seemingly setting any pciHole config.you can try to drop the memory down to 2 gb see if that resolves the issue with driver install. if it does, then you need to expand the pci hole size.
The hole need to be big enough for all the pci devices. so you might need to experiment and try numbers like 1200 - 4800 etc. I dont have an exact means of figuring it out but i read it somewhere that values might need to change base on vid memory.
pciHole.start = "1200"
pciHole.end = "2200"