Real Time Clock Module error "RTCDateTime" does not name a type.

I'm new to this website so I'm not 100% sure how to use it so just try to bear with me. I'm following "the most complete starter kit for mega V1.0.19.09.02.pdf" that I copied from the CD the kit came with. At lesson 19 "Real Time Clock Module" I ran into the error, Arduino: 1.8.9 (Windows Store 1.8.21.0) (Windows 10), Board: "Arduino/Genuino Mega or Mega 2560, ATmega2560 (Mega 2560)"

DS1307_Example:7:1: error: 'RTCDateTime' does not name a type

RTCDateTime dt;

^

C:\Users\chick\Desktop\Elegoo\code\Lesson 19 Real Time Clock Module\DS1307_Example\DS1307_Example.ino: In function 'void setup()':

DS1307_Example:15:9: error: 'class DS3231' has no member named 'begin'

clock.begin();

^

DS1307_Example:22:9: error: 'class DS3231' has no member named 'setDateTime'

clock.setDateTime(2020, 1, 15, 22, 37, 00);

^

C:\Users\chick\Desktop\Elegoo\code\Lesson 19 Real Time Clock Module\DS1307_Example\DS1307_Example.ino: In function 'void loop()':

DS1307_Example:31:3: error: 'dt' was not declared in this scope

dt = clock.getDateTime();

^

DS1307_Example:31:14: error: 'class DS3231' has no member named 'getDateTime'

dt = clock.getDateTime();

^

exit status 1
'RTCDateTime' does not name a type

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

Thanks ahead of time to all who can help! Sorry if I am too detailed, not detailed enough, or used the wrong details! I made sure to install the required libraries.

//www.elegoo.com
//2018.10.24
#include <Wire.h>
#include <DS3231.h>

DS3231 clock; 
RTCDateTime dt;       This is where it said the error was.

void setup()
{
  Serial.begin(9600);

  Serial.println("Initialize RTC module");
  // Initialize DS3231
  clock.begin();

  
  // Manual (YYYY, MM, DD, HH, II, SS
  // clock.setDateTime(2016, 12, 9, 11, 46, 00);
  
  // Send sketch compiling time to Arduino
  clock.setDateTime(2020, 1, 15, 22, 37, 00);    
  /*
  Tips:This command will be executed every time when Arduino restarts. 
       Comment this line out to store the memory of DS3231 module
  */
}

void loop()
{
  dt = clock.getDateTime();

  // For leading zero look to DS3231_dateformat example

  Serial.print("Raw data: ");
  Serial.print(dt.year);   Serial.print("-");
  Serial.print(dt.month);  Serial.print("-");
  Serial.print(dt.day);    Serial.print(" ");
  Serial.print(dt.hour);   Serial.print(":");
  Serial.print(dt.minute); Serial.print(":");
  Serial.print(dt.second); Serial.println("");

  delay(1000);
}

Did you install the DS3231 library.

If not, read this: