Support of OTA firmware updates for Z-Wave / Z-Wave Plus devices

Could you expand on how you eventually did this please.? I have many of these dimmers and they are not working correctly with the Generic Smart Z-Wave Dimmer driver. Support referred me to this thread.

Where do I get the Hex files - do I need to contact Leviton or is there a download I am unable to find with searches?
Did the z-wave stick that came with Hubitat work?
Do I need to get the software?

Amy other specifics.

Many thanks for your help.