Compatibility With Latest Version of WordPress

Did you try to use it?

This plugin doesn’t really do anything much from what I can tell, other than just add the standard excerpt box that you see on the post edit screen.

You can achieve the same thing with 3 simple lines of code in your functions.php file:

add_action( 'init', 'add_excerpts_box_to_pages' );
function add_excerpts_box_to_pages() {
     add_post_type_support( 'page', 'excerpt' );
}