I modified that key before I posted it as I wasn’t sure if there was any security issues with making it public. I got the key from the file /config/.storage/core.config_entries using the migration instructions for Zwave 1.4 to Zwave JS.
If you never had the Zwave 1.4 installed you should follow the instructions below. It looks like the key is automatically generated if you don’t provide one from a previous Zwave network.