maybe they have this in the documentaion in the wrong section?
Platform specific instructions
You do not need to install any software to use Z-Wave.
If the path of /dev/ttyACM0 doesn’t work, look in the System section of the Hass.io menu. There you’ll find a Hardware button which will list all the hardware found.
You can also check what hardware has been found using the hassio command:
$ hassio hardware info
Bash
The modemmanager package will interfere with any Z-Wave (or Zigbee) stick and should be removed or disabled. Failure to do so will result in random failures of those components. For example you can disable with sudo systemctl disable ModemManager and remove with sudo apt-get purge modemmanager