The LUX value is a condition but it will trigger the automation if the trigger sensor is ON. Example, if a motion sensor is ON and lux is high the light will be OFF but if the lux sensor goes low then the light will come ON.
If you would like to trigger on lux values then take a look at my 
Smart Light - Entity - Sun Elevation - Ambient & Time Triggers blueprint. I use this with sun elevation but lux value is similar, it will turn the light ON when sun elevation goes below falling value you could use lux value and then a 11pm I have it turn the lights OFF but you could use the lux value to turn the light OFF. You can mix and match what you would like.
I not sure exactly what you are trying to do but hopefully it may point you in the right direction.
Blacky 