Currently Arc II and Lightlapse are not integrated. This is something we may look into implementing in the future, however there is no timeline for that. In the meantime, this is how you can use Lightlapse with Arc II:
Arc II - Go into Advanced Time Lapse mode and change the menu type to Classic. (set through hardware, not the app)
Lightlapse - Select Classic menu type
Set the Interval, Number of shots, and shutter speed to match in both Lightlapse and Arc II. Press start on Arc II and in the Lightlapse app at the same time.
If you have any questions about this, please reach out to firstname.lastname@example.org