Widget on page not showing up

I’m currently coding my own one page wordpress theme (based on underscores) and I’m trying to add a widget to a page, so this widget will show up on my homepage.

I used this page as my guide; https://codex.www.ads-software.com/Widgetizing_Themes but the widget is not showing up on my homepage.

Steps I took:
1. Create a custom page template, this is the code of that:

<?php
/*
Template Name: Widget Page
*/

get_header(); ?>

	<div id="primary" class="content-area">

	<?php putRevSlider("video","homepage") ?>

		<main id="main" class="site-main" role="main">

			<?php dynamic_sidebar( 'widget-page' ); ?>

		</main><!-- #main -->
	</div><!-- #primary -->

<?php get_sidebar(); ?>
<?php get_footer(); ?>

Seems to work fine, I can select the template and the content of my page shows up on the homepage. (See test widget, test test test)

I added the line that calls on the widget there too, as you can tell.

Then I added this to my functions.php;

/**
 * Register our sidebars and widgetized areas.
 *
 */
function arphabet_widgets_init() {

	register_sidebar( array(
		'name'          => 'Widget Page',
		'id'            => 'widget-page',
		'before_widget' => '<div>',
		'after_widget'  => '</div>',
	) );

}
add_action( 'widgets_init', 'arphabet_widgets_init' );

And I think that’s where it’s going wrong? The underscores framework also comes with their own piece of widget code, is this causing problems?

/**
 * Register widget area.
 *
 * @link https://codex.www.ads-software.com/Function_Reference/register_sidebar
 */
function otto_widgets_init() {
	register_sidebar( array(
		'name'          => esc_html__( 'Sidebar', 'otto' ),
		'id'            => 'sidebar-1',
		'description'   => '',
		'before_widget' => '<aside id="%1$s" class="widget %2$s">',
		'after_widget'  => '</aside>',
		'before_title'  => '<h1 class="widget-title">',
		'after_title'   => '</h1>',
	) );
}
add_action( 'widgets_init', 'otto_widgets_init' );

This is a link to my page; https://kellyvuijst.nl/onepage/

Thanks in advcance!