I cannot find anything to suggest that this device supports any kind of positioning. It seems to just be a substitute for button pushing.
Having said that, this is the only description I found that spells it out as
Function up / down (without positioning)
No-one in this earlier thread seems to have it working
It would be possible to do some rough positioning using motor run time, but that’s not much use without a working STOP command. I guess the zwave database would need some tweaking to marry up the rollershutter type commands?