although this topic has been covered 9 months ago in this forum, the solutions mentioned there are not working in my environment. So I'm sorry to raise this problem again.
I'm still getting a fatal compiling error with the simple example sketch 'hello world':

/Users/matthias/Documents/Arduino/libraries/M5Stack/src/LoRaWan.cpp: In member function 'void LoRaWanClass::init()':
/Users/matthias/Documents/Arduino/libraries/M5Stack/src/LoRaWan.cpp:45:5: error: 'Serial2' was not declared in this scope
Serial2.begin(9600, SERIAL_8N1, 16, 17);
^
and

In file included from /Users/matthias/Documents/Arduino/libraries/M5Stack/src/LoRaWan.cpp:33:0:
/Users/matthias/Documents/Arduino/libraries/M5Stack/src/LoRaWan.cpp: In member function 'void LoRaWanClass::getVersion(char, short int, unsigned char)':
/Users/matthias/Documents/Arduino/libraries/M5Stack/src/LoRaWan.h:33:29: error: 'Serial2' was not declared in this scope
#define SerialLoRa Serial2******
^
... continuing with pages of consecutive error messages.
I'm using the Arduino IDE 1.8.10 with an M5CORE Grey and have removed and updated all relevant libraries, without any success.
Can anybody give me a hint where to dig ?
best regards