I receive the errors in attached image when attempting to install an app. Before this, I received the need uploader error which was solved with installing the "apps.php" from the following support link.
http://stackideas.com/forums/please-upload-an-app-installer
I have ES 1.3 and made sure to use the 1.3 version of the apps.php file.
Any attempts to install from /tmp directory are met with the following error
Temporary path specified does not exist on the server.
as you can see by image, the directory path exists and is writable.