I'd like to use your plugin but I am having the problem other people described. My site is at mysite.com/wp_XYZ/. When I install the widget and click on subscribe it goes to a 404 at mysite.com/wp_XYZ/wp_XYZ/.
In my settings both the WordPress Address (URL) and the Site Address (URL) are set to mysite.com/wp_XYZ. In admin_page.php I tried both home_url() and get_site_url() and get the same 404 (and as far as I can see they should both work).
Is there anything else I can try?
I'm on a self hosted site WP 3.5.2