How to use this library? about jsontospiffs HOT 3 CLOSED

#include <JSONtoSPIFFS.h>

#define CONFIGFILE "config.json"

JSONtoSPIFFS Config;

// Define some variables
bool setting1;
int setting2;
String setting3;

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

  // init library
  SPIFFS.begin();
  Config.begin(&SPIFFS);

  // set variables
  setting1 = false;
  setting2 = 343;
  setting3 = "hello world";

  // save config
  if (Config.loadConfigFile(CONFIGFILE)) {   // this will also create the configfile if it doesn't exists
    Config.setValue("mySetting1", setting1); // returns true on success
    Config.setValue("mySetting2", setting2);
    Config.setValue("mySetting3", setting3);
    Config.saveConfigFile(); // Commit changes
  }
  
  // change variables
  setting1 = true;
  setting2 = 100;
  setting3 = "no hello world";

  // load config
  if (Config.loadConfigFile(CONFIGFILE)) {
    Config.getValue("mySetting1", setting1);
    Config.getValue("mySetting2", setting2);
    Config.getValue("mySetting3", setting3);
    Config.closeConfigFile(); // dont forget to close the file!
  }

  // check variables
   Serial.println(setting1);
   Serial.println(setting2);
   Serial.println(setting3);

  // Remove "mySetting1"
  if (Config.loadConfigFile(CONFIGFILE)) {
    Config.removeKey("mySetting1");
    Config.saveConfigFile(); // Commit changes
  }

  // Delete configfile
  Config.deleteConfigFile(CONFIGFILE); // file has to be closed!
}

{ "Debug": true, "Device": "", "Serial": "AUT010001"}