The CC region with this driver is 171v. As long as the circuit has less you can be sure to get its full current(2,8A).
The open circuit voltage is higher and is 210v but if you use more like 171v it is out of it CC region and you don't see the full 2,8A. But it should work because 194v is far below the cut off voltage of the protection circuit(~216-246v)
So you can wire these 4 boards in series and you should at least get 2,6A or 500w. Maybe up to 550w cuz all these HLG drivers can have up to 8% more current. When the boards starts blinking(shut down and retry) its too much and you need another one. If not its safe and you get only a little less current and maybe invisible current fluctuations cuz its outside the CC range. But the driver would still try to put out a stable current.
The diodes are most probably LM301 and the little prongs, frame and all that matches with LM301b but its for sure not top bin. Top bin is always the most expensive and they would just don't use them for this reason. Its for sure also no 4oz copper PCB but 1 or maybe 2oz in the best case. There must be reasons why these boards are so cheap, no? I can get them for less than 30 bucks a piece.
But even if its not top bin the light is actually not bad at all. There are a few percent behind and don't reach the same efficiency but spectrum and all that is the same... unfortunately I must add!
They all are scammers(Meiju, R2T, Hanison, ..) and copy HLG's products. I would not use them even if they gifted me 100pcs just because I don't wanna support them in any way. What I have said here is more than they deserve.
I can understand when the budget is small but I do not like it when copying so boldly.
Be happy with it! When it works properly it will for sure grow some dank ass weed..