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.
This is a library for the Si5351 series of clock generator ICs from Silicon Labs for the Arduino development environment. It will allow you to control the Si5351 with an Arduino, and without depending ...