PID Speed Control Using Library

Hello! Up until now I have been using numerical approximations to do some motor speed PID control. I came across this library: GitHub - natnqweb/Motor_PID: //author:: Natan Lisowski // this library let you control motor with pwm signal

The sample code are controlling position not speed. I don't have enough knowledge/time to figure out how to modify this code to control speed instead. Could someone please help me?

Here's the code I would like to modify:

// remember that l298n need 3 volt over DC motor nominal voltage to run full speed 
//you can supply even more voltage but then limit it with pwm like i did here
#include <Motor_PID.h>
#define ENCA 2 // YELLOW from polulu encoder
#define ENCB 3 // WHITE from polulu encoder

#define IN2 10 //in2 from driver // pins to control direction
#define IN1 11 //in1 from driver // pins to control direction
#define PWM_PIN 5 //pwm to control speed

int target = 900;

// PID constants
float kp = 1;
float kd = 0.1;
float ki = 0.02;

int pwm_lower_limit = 0;//full range
int pwm_upper_limit = 255;//full range

Motor motor1(ENCA, ENCB, IN2, IN1, PWM_PIN, pwm_lower_limit, pwm_upper_limit);
void setup()
{
   motor1.init(kp, kd, ki);
   motor1.set_target(target);
}
void loop()
{
   motor1.start();
   if (motor1.get_position() == target) motor1.turn_off();
}

I'll attach a schematic just in case:

Thanks in advance

The same old project continued? Did the previous thread work out?

Why is precise speed needed?

Why not go back your previous attempts at speed control code and fix those instead?

It seems you have had lots of help on this forum, but it went nowhere.