To flash the firmware into the ESP32 board you will need to install the Arduino IDE and all the required libraries from the Libraries directory.

Here you can find a tutorial on how to install the libraries: https://www.arduino.cc/en/Guide/Libraries

Starting with 1.6.4, Arduino allows installation of third-party platform packages using Boards Manager. We have packages available for Windows, Mac OS, and Linux (32 and 64 bit).

• Install the current upstream Arduino IDE at the 1.8 level or later. The current version is at the Arduino website.
• Start Arduino and open Preferences window.
• Enter https://dl.espressif.com/dl/package_esp32_index.json into Additional Board Manager URLs field. You can add multiple URLs, separating them with commas.
• Open Boards Manager from Tools > Board menu and install esp32 platform (and don't forget to select your ESP32 board from Tools > Board menu after installation).