Seems to be some confusion. The smartstick plus is intended as a primary controller to be used with the Homeseer software.
The Homeseer software utility which can be used with SmartThings to update zwave devices OTA is the “z flash.”
You can buy the Z flash software separately in the homeseer store. Or you can buy a kit with the stick and the software. The software will run on a laptop.
You won’t be able to update zwave devices on your SmartThings network unless you also have the zflash software.
See The following FAQ (this is a clickable link)