Understanding this Mean Well Power Supply
With LED's you want constant current This keeps the LED's from exceeding their current rating and let's the designer avoid using a current limiting resistor or some other circuit to keep the current through the LED constant. 

This supply does both, but it depends on the load placed on it. It's a PWM driver, meaning it modulates the voltage to get the correct amount of current through the LED's. If the supply is in constant current mode (with the dimmer option with a 0-10V signal or PWM to go from 0 to 100%) then it will run from the voltage from 50% to Max. If you use 100% PWM then it will output it's full voltage.


You can string LED's in parallel and still use constant current.