Hi, can you just try putting this code into your theme's functions.php file?
add_action( 'mb_relationships_init', function() {
MB_Relationships_API::register( array(
'id' => 'posts_to_pages',
'from' => 'post',
'to' => 'page',
) );
} );
You'll see meta boxes "Connected From" and "Connects To" for posts and pages. It's the most basic usage.
Please try it.
