I have this exact 3-button switch but Tuya brand from Aliexpress (I think Zemismart is just seller brand)
Zemismart Zigbee Smart Remote Switch (3 button) driver - Get Help / Devices - Hubitat
There is a driver in that thread that you might try (I'm not using that), you need to modify it to 6 buttons I think.
I first used the built-in Zigbee Generic Multi-Endpoint Switch driver and it worked (it looks different now, I think it allowed to set no. of endpoint before)
In recent hub firmware update, seems it automatically moved the driver to Tuya Zigbee Scene Switch driver that you should try, make sure click "configure" after changing driver.
