This will not work with Arduino IDE 1.6.5 (or below) or with non ESP32-S2/S3 devices (e.g. Arduino UNO, Arduino MEGA, etc.). To use this library you need to have Arduino core for the ESP32 installed.
First read the Grove - Smart Air Quality Sensor (SGP41) and the Grove - AHT20 I2C Industrial Grade Temperature&Humidity Sensor documentation before reading this document. According to the SGP41 ...