You are downloading the Ubuntu Commands Reference XAP file v126.96.36.199 for Windows Phone. Ubuntu Commands Reference is a free Books & Reference App: This app is handy reference of commands used in ubuntu. You can now download the offline XAP package file to install & try it.
Download Locations for Ubuntu Commands Reference 188.8.131.52 XAP file
To try to install it manually from an SD card, you should choose one of the server location above to get the offline Ubuntu Commands Reference XAP file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.