Hello. Not sure if you managed to get this working yet, but if not, there is a ble library that ships with M5Stack Core2 Arduino install. #include <BLEDevice.h> on my computer this was installed at this location: .//Library/Arduino15/packages/m5stack/hardware/esp32/2.0.3/libraries/BLE/src/BLEDevice.h Hence I did not have to install the package separately. I have implemented a project using this just recently using a variety of BLE technology so confident that it works on at least my copy of Core2. If you go to the docs link from the library link you posted (https://github.com/nkolban/ESP32_BLE_Arduino) you can see that the project has now been directly incorporated into Arduino. The lib version you may have downloaded may be out of date. You can find BLEDevice.h/BLEDevice.cpp on your machine and check against the main Arduino source. Hope this helps?