New and Improved DFPlayer Mini Library!!

ovviamente!

#include <DFPlayerMini_Fast.h>

#if !defined(UBRR1H)
#include <SoftwareSerial.h>
SoftwareSerial mySerial(48, 50); // RX, TX
#endif

DFPlayerMini_Fast myMP3;

void setup()
{
  Serial.begin(115200);

#if !defined(UBRR1H)
  mySerial.begin(9600);
  myMP3.begin(mySerial);
#else
  Serial.begin(9600);
  myMP3.begin(Serial1);
#endif
  
  Serial.println("Setting volume to max");
  myMP3.volume(30);
  delay(20);
  
 
  myMP3.loop(1);
}

void loop()
{
 
}

schematics: 20210107_183048.jpg - Google Drive

the same code (obviously changing the TX and RX pins) on Arduino UNO works perfectly