SEN0395 mmWave + ESP32C3 error

So im trying the mmWave sensor using this ESP32C3 Board. I injeced the example code from the library with modified RX TX pin (21,20).

"

#include <DFRobot_mmWave_Radar.h>

HardwareSerial mySerial(1);

DFRobot_mmWave_Radar sensor(&mySerial);

int ledPin = 13;

void setup()

{

  Serial.begin(115200);

  mySerial.begin(115200, SERIAL_8N1, 21, 20);//RX,TX

  pinMode(ledPin, OUTPUT);

  sensor.factoryReset();    //Restore to the factory settings

  sensor.DetRangeCfg(0, 2);    //The detection range is as far as 9m

  sensor.OutputLatency(1, 2);

}

void loop()

{

  int val = sensor.readPresenceDetection();

  digitalWrite(ledPin, val);

  Serial.println(val);

}

"

And this is what i got from the Serial Monitor

what happened and whats wrong with my coding?