You are downloading the Yammer XAP file v220.127.116.11 for Windows Phone. Yammer is a free and useful Business app: Yammer is the best-in-class enterprise social network that makes your job easier and more productive. It brings together employees, content, ... You can now download the offline XAP file to install & try it.
Download Locations for Yammer 18.104.22.168 XAP file
Note: To install it manually from an SD card, you should choose one of the server location above to get the offline Yammer XAP file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.