To run this ESP-IDF project you have to install:
ESP-IDF v4.0.1 (support for Arduino as a Component)
Follow this guide to install it: https://docs.espressif.com/projects/esp-idf/en/latest/esp32/get-started/index.html#installation-step-by-step
It also specifies the prerequisites
When you have installed esp-idf you can run idf.py build flash monitor to build the project, flash it to a connected ESP32 board, and serial monitor it.