Aeon lab zstick and aeon lab zwave switch

I follow
CP210x.ko,

$sudo usermod openhab -a -G dialout
Although I do not have much idea about openhab user.

As mostly I use user xiaomin, I also do,
$sudo usermod xiaomin -a -G dialout

Now, both users in dialout group,
$grep dialout /etc/group
dialout:x:20:openhab,xiaomin

However, when I ./start.sh
I still got error below,
"Z-Wave Serial Controller
Z-Wave USB Stick with Serial Interface
Status: OFFLINE - COMMUNICATION_ERROR Serial Error: Port /dev/ttyUSB0 does not exist"

via paper UI from
http://localhost:8080/ui/index.html#/configuration/things/view/zwave:serial_zstick:1

Can some expert shed some light?
Thank you.