You are downloading the 3D Plot Grapher AppX file v188.8.131.52 for Windows Phone. 3D Plot Grapher is a free and useful Education app: A simple app that draws 3D graphs. With the help of the application, you can create fully customizable 3D graphics of mathematical functions, ... You can now download the offline AppX file to install & try it.
Download Locations for 3D Plot Grapher 184.108.40.206 AppX file
To try to install it manually from an SD card, you should choose one of the server location above to get the offline 3D Plot Grapher AppX file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.