Attachments not able to be read by computer programs

After applicants submits a form with attachment. It is successfully uploaded to the server, and by using File Manager Plugin, I can open it, download it and open it locally on my computer.

The issue then is, on applicants view page, when I click on attachment, it download, but can not be read by a PC. I get error messages. When attempting to open images, applications like Photos indicate that the file format is not supported, and for documents, Microsoft Word displays a message stating, “We found unreadable content.”