Your document states Voltage Out = LUX / 1333.
Do you understand that formula?
Your document shows the circuit you need to build.
Can you build that circuit?
1,000 Lux is an overcast day outside.
At 1,000 Lux, the circuit should generate about 1 Volt
across the resistor and into the Arduino A0 Analog Input.
The graph states, "Vr = 5 Volts".
So, I am assuming that is DVDD.
The PhotoDiode is Polarity Sensitive!
You are dealing with microamps, so noise will be an issue.
There are three connections to your circuit
Connect +5 Volts at the top
Connect Arduino A0 Analog Input to the middle
Connect ground at the bottom
Can you make these connections?
Maybe, a shielded cable?
If you can get that working,
and the Input Voltage is too low, at your lighting levels
then you may need to build a Non-Inverting Op-Amp circuit, too.