You would need to email
support@photopost.com with ftp and admin logins urls etc to look at the usergroup issue cause this is a very old integration and no one has ever reported issues so we need to see it
As far as users not being able to delete photos they click edit photo and there should be a delete box there now this is determined by two settings of course.
In admin options in admin you must have set that users can move delete their images?
In admin edit usergroups options you must set regular users able to edit their photos.