If you can't build the example code as like 'Hello world'.

[tann]

I just success building examples on OSX. (Arduino 1.8.5 and M5Stack 0.0.5)
There must be two "M5Stack-Core-ESP32" in Tools -> Board menu.
You should choose 2nd "M5Stack-Core-ESP32" term and then try to build.
Have a wondeful day.