"The security model on the Galaxy S6 requires that you disable SELinux in order to give LeapDaemon access to the USB stack. And this of course requires rooting the device.
Once you have the device rooted, run setenforce 0 to disable SELinux. Unfortunately you'll have to rerun this anytime you boot the device.
Compared to the Note 4 where we would replace the USB plug, using a Leap Motion on the Galaxy S6 / Gear VR 2 typically involves using the external USB plug on the headset. However, this then forces one into Oculus Mobile SDK mode. Thus, it's kind of hard to use the Cardboard SDK and now you're compelled to link with the Oculus Mobile SDK which carries the various hassles including the required Oculus signature file.
You don't need an additional hub, but the current situation with the Galaxy S6 / Gear VR 2 is certainly less than ideal."
via Team Leap Motion, member
This was a comment to a post on the Leap Motion community forums.