I’ve installed a new Zooz 800 series USB device for this purpose. I installed the z-wave integration, and then z-wave js, and finally z-wave js ui.
You can’t run the Z-Wave JS core add-on and Z-Wave JS UI community add-on at the same time, that is likely your problem. You could always follow the guide for a streamlined migration to ZUI:
Since I only installed less than 20 devices, I’ve decided I just want to start over and remove all the devices in Home Assistant, clear the USB Stick, and finally remove all the add-ons and integrations related to z-wave so I can start again.
Resetting the stick and remove the devices is a really just a complete waste of time. Deleting the integration from HA will remove all the devices from HA. You can then uninstall the core add-on. You don’t even need to uninstall Z-Wave JS UI, continue using it and connect it to HA according to its documentation.
As a follow-up, what would then be the proper steps to install z-wave support to use z-wave js ui from the start?
If you want to start with Z-Wave JS UI, follow the instructions, which are in the documentation of the add-on, visible from the Docs tab on the add-on page, or at https://github.com/hassio-addons/addon-zwave-js-ui/blob/f8a02dbe8143dad77b5315f49bac9ddc5fcff5a0/zwave-js-ui/DOCS.md#setting-up-the-home-assistant-z-wave-js-integration.