The error is saying that there is a problem with the permissions on the upload folder at:
make sure that the /PDF/ directory on your server has the proper permissions to upload files.
You may be able to use Dreamweaver for this, if the site definition has the remote or testing server set to use your remote host. In the Files panel chose either Remote View or Testing Server View, whichever is configured to connect to the remote host. Right Click The PDF directory and select Set Permissions. Set OWNER to Read Write Execute, Set User/ Group to Read, Write and set Everyone to Read, Write.
If you cannot modify the permissions using Dreamweaver, you will have to use another FTP program.