It may be that the server does not recognize the Currant form submit trigger, try changing the trigger in the download behavior from Currant page submit to any form post.
also double check that the files to download exist in the loacation you are telling the download behavior to look in.
You have set the download location to:
I see in the source, the hiddenform field is correctly getting a file name:
<form id="form1_1" name="form1_1" method="post" action="">
<input type="hidden" name="hiddenField" id="hiddenField" value="1.pdf" />
<input type="button" id="download" name="download" value="Download" />
so it will be looking for the file at:
This is a path relative to the document,
So if the download center page is at:
it is looking for the downloads folder 2 directories down:
double check that the relationship is correct.