You are downloading the Xbox Music XAP file v2.6.657.0 for Windows Phone. Xbox Music is a free and useful Music app: Xbox Music brings you all the music you love in one simple to use app. Play and manage your personal music collection, buy songs from the Xbox Music ... You can now download the offline XAP file to install & try it.
Download Locations for Xbox Music 2.6.657.0 XAP file
Important Notice: Now Due To Unspecified Limitations, You Can Not Use The Offline XAP File To Install It Any More.
To try to install it manually from an SD card, you should choose one of the server location above to get the offline Xbox Music XAP file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.