please check your ".htaccess" file which should reside in the ezpublish installation directory right beside index.php .
Locate the lines which might reflect access restrictions to folders under /var/... and/or filetypes. If you are using the stock htaccess-root file, change the following lines
But of course you can and should use a more specific rule other than globally enable access to pdf-files like I did above. Please ensure not to open (in terms of security) your server. Also make sure to understand the terms above before adding them to your server.
Of course it might be possible, that "Access denied" comes from a complete other source and the stuff above is not the cure.