Hi,
Thank you for your reply and thanks for the welcome! 
I had the temp probe connected to the Fibaro Universal sensor from the start, but in the Devices menu (pic 1 below) no new device was added (where I expected a new device for the temperature probe or the Universal Sensor?). Under the menu More… > Apps >, a Fibaro app appeared (pic 2 below), but it says ‘This app does not have any devices yet’.
Today, I removed the extension cable and put the temp probe together with the sensor again. Then I uninstalled the Fibaro app, removed the Z-wave device, reset the Z-wave network, reset the Fibaro Universal Sensor, tried to install the Fibaro unit again, run the CLI command. It didn’t work to install the Fibaro. I got time out error, which could mean badly connected cables? I’ll try to get some better wire connectors tomorrow, to make sure the connections are good. Then I’ll give it another try.
I guess the CLI command should be run after installing the Fibaro Unit, to overwrite the firmware?
Thanks for the advice! 
Pic 1:
Pic 2:
