The Heiman Zigbee app isn’t available on the community store:
Are you looking for this app?
You need to install it via Homey CLI. Someone created a How To for that here:
Thanks again Sven much appreciated! I got quite far but combination macOS and CLI is not the easiest:) Will try a bit more later. However it is odd Heiman app is not working at all, even though it is a Heiman device…
The Heiman app only supports Z-Wave devices, while your device is a ZigBee device. This is why it’s not working with the Heiman app
That makes sense 
So finally I tried the zigbee app (from GitHub). It is supported for version 5.0.0. I updated the file so it supports 12.12.0, the app appears in Homey but is not possible to add the zigbee Heiman smoke detector. At this point I give up
