I think the best way would be to use the plugin coded by the generatepress lead programmer:
Hello,
I have downloaded the plugin made by the Generatepress Author “WP show posts” with the right settings.
After installing the plugin, I created a post list by going to WP show posts in the sidebar of my installation. Then, on the right side of the screen, I copied the PHP function located on the right side of the screen in my clipboard.
Then, I created a new element (premium feature) by visiting Appearance > elements, with a hook, generate after content with the following code, I pasted the PHP code that I have copied from the WP show posts plugin. So in the following code below, replace the php with the php you copied from wp show posts
<div>
<hr>
<h2>Related Posts:</h2>
<?php if ( function_exists( 'wpsp_display' ) ) wpsp_display( 46457 ); ?>
</div>