How to properly connect MySQL to Qt5.4?

Question

MySQL

The problem is quite hackneyed, but still, I ask for help, I'm stuck in this very much.
Downloaded installed.
After the operations that were not done quite accurately, due to the inaccuracy of the instructions, I decided to compile a code example.
I get that there seems to be a driver for QMYSQL, but I still get an error.
I would be incredibly grateful for step-by-step instructions on how to fix and still connect the DBMS to Qt.

//main.cpp
#include "widget.h"
#include <QApplication>
#include<QSqlDatabase>
#include<QSql>
#include<QDebug>
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    qDebug() << QSqlDatabase::drivers();
    Widget w;
    w.show();

    return a.exec();
}

//widget.cpp конструктор
#include "widget.h"
#include "ui_widget.h"
#include<QDebug>
#include<QSql>
#include<iterator>
#include<QSqlDatabase>
#include<QSqlQuery>

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
    db.setHostName("localhost");
    db.setDatabaseName("mysql");
    db.setUserName("root");
    db.setPassword("rootPW");
    if (!db.open()) qDebug() << "Failed to connect to root mysql admin";
    ui->textEdit->setReadOnly(true);

}

as a result, something like this is output to the console:
Running D:\Qt projects\build-History-Desktop_Qt_5_4_1_MinGW_32bit-Debug\debug\History.exe...
("QSQLITE", "QMYSQL", "QMYSQL3", "QODBC" , "QODBC3", "QPSQL", "QPSQL7")
Failed to connect to root mysql admin