Yeah, the red connector (CN4) is just a header to connect a backlight driver to the main board and bring 5v to the board from the power supply. Usually, the backlight driver is on the same power supply board that gives 5v to the display board.
It has two grounds, two 5v pins, adjust brightness and enable (on/off or something like that)
If the panel has a built in backlight driver on the panel board, it should have pins with ground, voltage, adjust, enable pins.
If it's just wires connected directly to the led strips, you need a backlight driver board.
See datasheet, from page 15 onwards :
https://www.beyondinfinite.com/lcd/Library/Auo/B101XTN01.1.pdfIt says there backlight section needs minimum 6v, maximum 21v, and typical is 12v ... it also says that maximum backlight power is 1.8 watts
So basically 18v x 0.1A = 1.8 watts , 12v x ~ 0.15-0.20 A is 1.8w ... 6v x 0.3 A is 1.8w
Page 18 tells you the 40 pin connector pinout, here's the last pins

So the last 3 pins on your 40 pin connector are voltage (at least 6v), LED_EN is the on/off , enable pin, most likely last pin on the red header, PWM goes to that ADJ pin on the red header.
So I would use a 7.5v/9v/12v power supply and then use a small 5v linear regulator to give power to the board and therefore the lcd panel.