If you go to the URL https://nadlancz.com/page/2/ you'll see that navigation works.
What you need to do to see the navigation links is add something like this to your page
<!-- Navigation -->
$pagination = get_the_posts_pagination(array(
'mid_size' => 2,
'prev_text' => 'Previous',
'next_text' => 'Next',
The code is in wp-includes/general-template.php.
However there aren't any great options for styling the output: there's a hook for you to modify the link URL, but nothing else. Your best bet might be to call it in type=array mode
$links = pagination_links([ "type" => "array" ]);
which will return you an array of strings of links of the form
If you have a form you should have a sort field in it, so that you can send your order value on form submit. This way you can send the sorting parameter to your backend callback function.
If you don't have a form you shoud add this parameter to another element with a data attribute like that:
<button id="load-more" data-order="DESC">Load More</...