You are downloading the Facebook Mobile 8.1 XAP file v18.104.22.168 for Windows Phone. Facebook Mobile 8.1 is a free Social App: No Advertising!!! For a limited time - "FREE"! Download Now! Facebook for Windows 8 Phone makes it easy and convenient to stay. You can now download the offline XAP package file to install & try it.
Download Locations for Facebook Mobile 8.1 22.214.171.124 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 Facebook Mobile 8.1 XAP file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.