Add paypal donate button in the menu

pp_donate_menu_item.php

function get_ppdonate_form( $echo = true ){
    ob_start();
    // replace value="XXXX" with your button id
?>
    <form action="https://www.paypal.com/cgi-bin/webscr" method="post" target="_top">
        <input type="hidden" name="cmd" value="_s-xclick">
        <input type="hidden" name="hosted_button_id" value="XXXX">
        <input type="image" src="https://www.paypalobjects.com/en_US/i/btn/btn_donate_LG.gif" border="0" name="submit" alt="PayPal – The safer, easier way to pay online!">
    </form>
<?php
    $form = ob_get_contents();
    if ( $form ) ob_end_clean();
    
    if ( $echo ) 
        echo $form;
    else
        return $form;
}
add_filter('wp_nav_menu_items', 'add_ppdonate_form_to_menu', 10, 2);
function add_ppdonate_form_to_menu($items, $args) {
 
// If this isn't the main navbar menu, do nothing
if( !($args->theme_location == 'main') )
    return $items;
 
    // On main menu: put class around the form and append it to the menu items
    return $items . '<li class="my-nav-ppdonate">' . get_ppdonate_form( false ) . '</li>';
}

Thanks code working for me