CPT

Looks like you just need to specify the posts you want to be considered, via this available filter:

$allowed_post_types = apply_filters( 'sitewide_tags_allowed_post_types', array( 'post' => true ) );

Are you familiar with WordPress filters at all? If not, I can type up a quick sample code that you can adjust.

Hi, It would be awesome if you can provide me with a snippet i can adjust with my custom post type name ( books)

Try this:

function custom_wds_multisite_aggregate( $post_types ) {
	$post_types[] = 'books';

	return $post_types;
}
add_filter( 'sitewide_tags_allowed_post_types', 'custom_wds_multisite_aggregate' );

Should be ready for you. This will be a snippet that goes in your active theme’s functions.php, or whatever place you may have for custom code snippets.