You really don't want to cheap out on motherboards, without a manual and being a no name brand, there's no way to know what anything does.
Some options might be random or do nothing.
And maybe the NVME hookup is broke or never real to begin with.
You could mess around and try to get it working, but you're risking it breaking other components. Even if you have to buy the cheapest brand name motherboard, I'd make that a priority.