if your LED is looking for 100 watts, you want to pick a 100 watt driver.
you will find them in 20V, 32v, 38v, 42v, 48v... etc.
the voltage range is often in the 50% to maximum, meaning you cannot use them to power less than the voltage that is 50% of the maximum. some are more like 10volts minimum, some a little less.
the idea is that there has to be come juice left over to use to measure !
as was stated your LED is probably using 3 to 6 volts.
let's use 6 volts.. if you have 6 LED, at 6 volts, the total voltage drop would be 36 volts.
a 38v driver would probably have a lower voltage level of 18 volts, meaning you would have to use 3, but no more than 6.
also, you do not want to run near or at maximum. typically a safe area is up to, but not more than 80%
the more you spend on the driver, the closer to the maximum you can push your circuit. I have had some of the cheap chinese versions fail at a 70% load. the Fulham drivers, the ThoroLED can be pushed a lot closer to maximum, but cost 3 to 4 times more