TThere are two kinds of Z wave commands.
One kind goes to the hub.
The other kind goes directly between two end devices. Both of these devices have to be using Z wave to communicate, and they have to be within range of each other, typically in the same room. (Hue bulbs are zigbee devices, so they cannot be used in this way.)
If you have a Z wave only system, and you aren’t using a mobile app for status, then you might set up something like this so that a motion sensor would directly trigger a light. Or, for a zone controller such as this one, so that A zone controller could send a message to other devices in the same room. Because they aren’t going to the hub, they are limited to “one hop.” ( and again, all the devices have to be zwave.)
Most people don’t use those kind of devices with a multiprotocol platform like smartthings, or, to be honest, with any system where you going to want to use a mobile app, because since the hub doesn’t know about the activity, the mobile app won’t either and everything gets out of sync.
The Leviton zone controllers, as has been discussed several places in the forum, are old style devices intended for the kind of communication that doesn’t go through the hub. So that’s why the hub is not getting any information from that 5th Button.
There are a number of other devices which will work with a multiprotocol platform and will let you press a button on the wall on a Z wave device, have that talk to the hub, and then have the hub send a message to a zigbee or WiFi device. But they aren’t this particular model.