Transmitting GPS coordinates with LoRa RFM95 (Multi-hop communication)

Hello everyone,
Hi I'm making a project using LoRa RFM95 and UBLOX GPS. The project that I'm working on uses a multi-hop system (RH_ROUTER) for sending data.
I am very beginner in using this programming language and i'm still learning. When I compile the code that I made, I get this error message

 'SerialUSB' was not declared in this scope'

I really need help in working on this code. Any help is highly appreciated!. Maybe you can help me improve the code that I use this.
Here is the code that I use on my transmitter:

#include <RH_RF95.h>
#include <SPI.h> //RadioHead Library
#include <Wire.h> //Needed for I2C to GPS
#include "SparkFun_Ublox_Arduino_Library.h" //http://librarymanager/All#SparkFun_Ublox_GPS
SFE_UBLOX_GPS myGPS;

RH_RF95 rf95(12, 6);

//int LED = 13; //Lora Status LED
long lastTime = 0; //Simple local timer. Limits amount if I2C traffic to Ublox module.
float frequency = 921.2;

void setup()
{
  SerialUSB.begin(115200);
  //while (!Serial); //Wait for user to open terminal
  Wire.begin();
  SerialUSB.println("RFM Server");

  if (rf95.init() == false){ //Initialize the radio
    SerialUSB.println("Radio Init Failed - Freezing");
    while (1);
  }
  else{
  // An LED indicator to let us know radio initialization has completed.
    SerialUSB.println("Receiver up!");
    //digitalWrite(LED, HIGH);
    delay(500);
    //digitalWrite(LED, LOW);
    delay(500);
  }
 
  if (myGPS.begin() == false) //Connect to the Ublox module using Wire port
  {
    SerialUSB.println(F("Ublox GPS not detected at default I2C address. Please check wiring. Freezing."));
    while (1);
  }

  rf95.setFrequency(frequency);
  //rf95.setTxPower(14, false); //This will be used to set the power of the radio, set it between 5 to 23 dBm
  //myGPS.enableDebugging(Serial);

  myGPS.setI2COutput(COM_TYPE_UBX); //Set the I2C port to output UBX only (turn off NMEA noise)
  myGPS.setNavigationFrequency(20); //Set output to 20 times a second

  byte rate = myGPS.getNavigationFrequency(); //Get the update rate of this module
  SerialUSB.print("Current update rate:");
  SerialUSB.println(rate);
 
  myGPS.saveConfiguration(); //Save the current settings to flash and BBR

}

void loop()
{
  //Query module only every second. Doing it more often will just cause I2C traffic.
  //The module only responds when a new position is available
  if (millis() - lastTime > 0)
  {
    lastTime = millis(); //Update the timer
    SerialUSB.print("HP Lat: ");
    int32_t latitude = myGPS.getHighResLatitude();
    SerialUSB.print(latitude);
    delay(250);
   
    SerialUSB.print(", HP Lon: ");
    int32_t longitude = myGPS.getHighResLongitude();
    SerialUSB.print(longitude);
    delay(250);
   
    SerialUSB.print(", HP Alt: ");
    int32_t altitude = myGPS.getAltitude();
    SerialUSB.print(altitude/1000);
    delay(250);
   
    //SerialUSB.print(", Accuracy: ");
    //uint32_t accuracy = myGPS.getHorizontalAccuracy();
    //SerialUSB.println(accuracy);

    //SerialUSB.print(", 3D Accuracy: ");
    //uint32_t DAccuracy = myGPS.getPositionAccuracy();
    //SerialUSB.print(DAccuracy);
    //SerialUSB.print(" mm");
    //delay(500);

    SerialUSB.println("Sending message");
    //add 200
    const int8_t toSendlat = latitude;
    const int8_t toSendlon = longitude;
    const int8_t toSendalt = altitude;
    uint8_t sendarr [3] = {0};
    sendarr[0] = (uint8_t) toSendlat;
    sendarr[1] = (uint8_t) toSendlon;
    sendarr[2] = (uint8_t) toSendalt;
    rf95.send(sendarr, sizeof(sendarr));
    rf95.waitPacketSent();
    SerialUSB.println("Sent message");



    delay(250);
 
  }

}

Which Arduino are you using? Did you select the correct board before compiling?

We recommend that beginners start by working through some of the simple examples that come with the Arduino IDE. Save yourself endless frustration.

I use arduino uno for this project and and I'm sure I've chosen the right board and thanks for your advice, I might understand about programming with arduino but by that I mean I'm still a beginner with LoRa but I have to finish the project that I'm working on

That code was not written for the Arduino Uno.

For the Uno, you would use Serial.begin(), which you would know if you had worked through a couple of the examples I mentioned.

At the very least, you need to change all instances of SerialUSB to Serial. There may be many more problems.