With WPPA you can also upload PDF documents. The document - or the first page of a multi page documnet - is converted to a .jpg file during upload, and works like any other 'normal' .jpg file (photo).
The original .pdf file is saved in the photo sources folder and will be available for download.
This feature requires that you have ImageMagick installed on the server, and that you activate it in wppa, see also this documentation page.
When activated in Table IV-A30 and ImageMagick works, you can upload pdf files at the front-end and in the boxes A and B on the Photo Albums -> Upload Photos admin page.
To make the original pdf files downloadable by the user, simply add to the photo description the keyword: w#pl. This will display the permalink to the pdf document. Note: it may take up to one hour after the creation of a new album to get the permalinks w#pl start working. You can NOT use the Download link (Art Monkey link) as configurable in Table VI-C1.x for this purpose. If you want a button for the download put this code in the description of the photo (pdf document):
<input type="button" style="margin:0 auto;" onclick="window.open('w#pl', '_blank')" value="Download w#filename" />