I no longer use the built-in version of zwave for my Home Assistant Setup, but I found a post with screenshots that can hopefully walk you through the process.
For my Red Series dimmers/Ilumin bulbs, I set up associations on groups 2, 3 and 4.
- Group 2 gives you on/off control
- Group 3 also gives you on/off control (it seems to work fine if you dont associate this group, but it doesnt seem to cause any issues either way)
- Group 4 gives you dimming functionality
Dont forget to disable the relay on the switch (config button x8).