Pass Success Message from PHP to HTML page after validation

I’m tiring to Pass a success message after pup checks the database and confirms the data
how do I display a message in case of a wrong password entry ,I tried many solutions with no success ,I tried using ajax solutions and JavaScript with no success as I don’t know the basics on ajax and my background in JavaScript is basic
Here’s my code

LoginTest.html

<html>
<link rel="stylesheet" href="LoginStyle.css">
<head>
    <title>Login</title>
</head>

<body>

    <div class="login-box">
        <h2>Login</h2>
        <form action="http://localhost/Test2/dbloginTest.php" method="post" name="loginform" class="loginform">
            
            <div class="user-box">
                <input type="number" name="civilid" required="">
                <label>Civil ID</label>
            </div>

            <div class="user-box">
                <input type="password" name="password" required="">
                <label>Password</label>
                
            </div>
            <input type="submit" name="submit" Value="Login">
        </form>
        
        <a href="Registration.html">
            <input type="submit" name="register" Value="Register">
        </a>

    </div>


</body>

</html>

dbloginTest.php

   <?php
require 'C:WindowsSystem32vendorautoload.php';
if (isset( $_POST['submit'] ) && isset( $_POST['civilid'] ) && isset( $_POST['password'] ) ) {

    $civilid = ( $_POST['civilid'] );
    $password = ( $_POST['password'] );
    $hashpass = "";
    $return = array();
    //echo extension_loaded( "mongodb" ) ? "loadedn" : "not loadedn";
    $con = new MongoDBClient( 'mongodb+srv://Admin:[email protected]/?retryWrites=true&w=majority' );
    // Select Database
    if ( $con ) {
        $db = $con->VoterDatabase;
        // Select Collection
        $collection = $db->Voters;
        $cursor = $collection->find( array( 'civilid' => $civilid ) );
        foreach ( $cursor as $row ) {
            ob_start();
            echo $row->password;
            $hashpass = ob_get_clean();
        }
        
       
        if ( password_verify($password,$hashpass) ) {
            echo "You Have Successully Logged In";
            header( 'Location:Voters.html' );
            exit;
        } else {
            
            echo "Your Civil ID or Password is Incorrect";
            header( 'Location:LoginTest.html' );
            exit;
        }
    } else {

        die( "Mongo DB not connected" );
    }
}
?>