Files Will Not Download
If your file will not download it may simply be because you are not in wifi and the file is large.
If it downloads ok but will not open its likely because you do not have a PDF reader installed. For your laptop/PC, just google search ADOBE PDF READER and you can download this for free in just 2-3 minutes.
If you are using from your iPhone, smart phone or tablet, then, you can simple search the same key words, ADOBE PDF READER in your app store and download a free or paid version. Once you've done so, your files should work without an issue like they do for thousands of people.