You are downloading the Guitar Player XAP file v22.214.171.124 for Windows Phone. Guitar Player is a free and fun Music game: Try to play on WP7 Guitar and create your own ... You can now download the offline XAP file to install & try it.
Download Locations for Guitar Player 126.96.36.199 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 Guitar Player XAP file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.