Previous/next item link

I’m just starting to play with Omekas. I have encountered a problem that I can’t solve. I want to add previous / next buttons to easily browse next item. Such buttons were in the Omeka Clasic. I found the Next module, which according to the description adds such functionality. I installed. But the “Disable previous / next” option doesn’t work. It’s unchecked. I’m using the mariadb database. The previous / next buttons in the item view do not appear. Can you help me add such buttons?

It is inserted automatically in admin, but it should be added manually in the theme.
As an example:

$plugins = $this->getHelperPluginManager();
$hasNext = $plugins->has('previousResource');
<?php if ($hasNext): ?>
<div class="previous-next-items">
    <?php if ($previous = $this->previousResource($resource)): ?>
    <?= $previous->link($translate('Previous item'), null, ['class' => 'previous-item']) ?>
    <?php endif; ?>
    <?php if ($next = $this->nextResource($resource)): ?>
    <?= $next->link($translate('Next item'), null, ['class' => 'next-item']) ?>
    <?php endif; ?>
<?php endif; ?>

Hmm. There is no mention of this code in the plugin documentation.
I add this code to the theme, but unfortunately it doesn’t work.
After adding the code, the blank page is displayed.

This is a code i use in a living site.
Display the log to see the issue.