You can download [J-Link Software and Documentation pack](https://www.segger.com/downloads/jlink/) that includes a flash programming tool `J-Flash Lite`.
A `.hex` file can be flashed using `J-Flash Lite`.
Please refer to the [Getting started with MicroPython on the Renesas RA](https://docs.micropython.org/en/latest/renesas-ra/tutorial/intro.html) about cable connection between the board and your PC.