You are downloading the Docs Viewer AppX file v188.8.131.52 for Windows Phone. Docs Viewer is a free and useful Productivity app: Docs Viewer allows you to quickly view documents on Windows devices, including PDFs and Microsoft Office Files. Supported file ... You can now download the offline AppX file to install & try it.
Download Locations for Docs Viewer 184.108.40.206 AppX file
Note: To install it manually from an SD card, you should choose one of the server location above to get the offline Docs Viewer AppX file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.