How to make both bits of code run at the same time

Hey everyone i am very new to Arduino and c++ and was struggling with some code and was hoping someone can just tell me whats wrong and i can fix it.

Basically i am trying to get a traffic light and a receiver script to run the same time. Currently what happens is once the light cycle is over it runs the receiver code once and only captures one signal being transmitted. I want it to be constantly ready to receive information from the transmitter.

I have tried creating two seperate functions but it still either doesnt work (no lights) or it does the once a cycle thing

#include <RH_ASK.h>
#include <SPI.h>

int ledPins[] = {2,3,4};
RH_ASK rf_driver;

void setup() {
  int index;
  for (index = 0; index <= 2; index++) {  // Intilaize ASK object 
    rf_driver.init();
    // Setup Serial Moniter
    Serial.begin(9600);
  }
  {
    pinMode(ledPins[index], OUTPUT);
  }
}

void loop() { /****** LOOP: RUNS CONSTANTLY ******/
  int oneAfterAnotherLoop();
  int RadioController();
} //--(end main loop )---

void oneAfterAnotherLoop() {
  int delayTime = 100;
  digitalWrite(ledPins[0], HIGH);
  delay(4000);
  digitalWrite(ledPins[0], LOW);
  digitalWrite(ledPins[1], HIGH);
  delay(5000);
  digitalWrite(ledPins[1], LOW);
  digitalWrite(ledPins[2], HIGH);
  delay(4000);
  digitalWrite(ledPins[2], LOW);
}

void RadioController() {
  uint8_t buf[19];
  uint8_t buflen = sizeof(buf);
  if (rf_driver.recv(buf, &buflen)) {
    Serial.print("Message Recived: ");
    Serial.println((char*)buf);  
  }
}

#include <RH_ASK.h>
#include <SPI.h>

int ledPins[] = {2, 3, 4};
RH_ASK rf_driver; // Intilaize ASK object 

void setup() {
  rf_driver.init(); //start rf_driver
  Serial.begin(9600); //begin serial
  for (int i = ledPins[0]; i <= ledPins[(sizeof(arr) / sizeof(arr[0])) - 1]; i++) {
    //set every pin in ledPins to output (flexible, if ledPins changes no need to change the loop)
    pinMode(ledPins[i], OUTPUT);
  }
}

void loop() {
  RadioController(); //only call RadioController() in loop, since oneAfterAnotherLoop() is now called there
}

void oneAfterAnotherLoop() { //left untouched
  digitalWrite(ledPins[0], HIGH);
  delay(4000);
  digitalWrite(ledPins[0], LOW);
  digitalWrite(ledPins[1], HIGH);
  delay(5000);
  digitalWrite(ledPins[1], LOW);
  digitalWrite(ledPins[2], HIGH);
  delay(4000);
  digitalWrite(ledPins[2], LOW);
}

void RadioController() {
  uint8_t buf[19];
  uint8_t buflen = sizeof(buf);
  if (rf_driver.recv(buf, & buflen)) {
    Serial.print("Message Recived: ");
    Serial.println((char * ) buf);
  }
  oneAfterAnotherLoop(); //call the loop down here (since most arduinos are singlethreaded, prioritize the listening for communications)
}