Grove - Multichannel Gas Sensor v2 - Flashing Firmware Instructions and connectivity

I have requested to make a new PCB size through Seeed Fusion from the same schematics of Grove - Multichannel Gas Sensor v2. The firmware of the Multichannel Gas Sensor v2 had not been flashed/uploaded to the MCU of the device. I have been given the firmware but the instructions is using the Seeed hardwares only.

Any ideas on how to flash the firmware to the MCU from my PC, what hardwares to be used and its connectivity from PC to the MCU of Multichannel Gas Sensor v2?

Thanks for the help in Advance!