You are downloading the Dev Resources for Unity AppX file v126.96.36.199 for Windows Phone. Dev Resources for Unity is a free and useful Business app: News and reference app for Unity 3D Content Creators and Developers. This app is not published or sponsored by Unity ... You can now download the offline AppX file to install & try it.
Download Locations for Dev Resources for Unity 188.8.131.52 AppX file
Note: To install it manually from an SD card, you should choose one of the server location above to get the offline Dev Resources for Unity AppX file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.