Sortd requires IMAP access to be able to access metadata about your email (See Does Sortd store my email) as well as access to the Google+ API's. If you are using a Google Apps domain account it is possible for your Google Apps Domain Administrator to deny access to IMAP and the Google+ API's in which case Sortd will unfortunately not work. Note that you don't actually need a profile in Google+, just access to the Google+ API's. This is because Google now do all authentication through Google+ and not simply through Gmail anymore.
For further information on validating Google Apps Domain settings, please view these instructions.