Arduino for STM32

I am upgrading my keypad project from the Arduino Pro Micro to STM32F103.
However, I have a problem using LibMaple (Roger's repo).

Arduino Pro Micro (Atmega 32U) code

#include "Keyboard.h"

void setup() {
Keyboard.begin();
}

void loop(){
Keyboard.press(KEY_F13); //Arduino Built-in F13 ...