Modifies the login URL sent to new users via email.
<?php
/*
 * Plugin Name: Easy Digital Downloads - Change Registration Login URL
 * Description: Modifies the login URL sent to new users via email.
 * Author: Easy Digital Downloads
 * Author URI: https://easydigitaldownloads.com/
 * Version: 1.0
 */

add_filter( 'edd_user_registration_email_login_url', 'eddcustom_modify_user_login_url' );
/**
 * Modifies the login URL for the default user registration email.
 *
 * @return string
 */
function eddcustom_modify_user_login_url() {
	return 'https://www.google.com/login';
}
To implement this snippet on your site, create a brand new, empty WordPress plugin and paste the above code inside.