It's a bit tricky to use with 5e, compared to 3.5 or 4th. You'll want to go to the token's light setting, and have it produce light out to the radius of the ddarkvision (or some very high number if it is infinite range, haven't played much 5e, can't remember). Then, put the Start of Dim Light value to 0. Lastly, make sure that the "all players see light" button is NOT checked. The light multiplier won't actually make any dim light to be bright, but will make the radius of any light, bright and dim, to be twice as wide. his works very nicely with 3.5/PF low-light vision, but not so much 5e darkvision. If you do choose to leave it on (since you can't really get exactly correct results either way) make sure to set any light ranges that only that character can see (like the example above) put the distance at half the value. For example, if the character has some special vision that works out to 60 feet, set the value to 30, because it will get multiplied by 2, like all other light sources.