When I run the install script, I get the photopost configuration verification screen (where I can input the database information), but when I click on save changes, I get a 403 error:
Forbidden
You don't have permission to access /photos/install.php on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.
I've uploaded the whole folder, and I've got all the permissions set as per the installation guide found here:
http://www.photopost.com/installphp.html