All I know about it is that the first time I tried setting up an attachments folder, I got stumped entering the path correctly. You may need to enter a full path (which may include a lot of stuff you are not aware of, if you are on a shared host or something), or a relative path that may not start where you think it should.
Anyway, the simple answer is to create your attachments folder as a direct sub-folder of the "scp" folder.
So, in my case i created the folder domain.com/osticket/scp/attachments
...then check the permissions on this attachments folder.
Then, in the admin panel where it asks for the folder for attachments, I enter simply "attachments" (with no path, and no quotes). should work fine.
(and by the way, after you enter the folder name and click "Save Changes", if you entered a valid folder name then the text in the form will change to show you the full path to your attachments folder.)