Iam unable to Install as an Admin on my Domain using my mobile/cell phone.
This is a limitation of the Chrome Webstore. It is true for all Google Apps installations for any marketplace app. Please see the link : http://googlesystem.blogspot.de/2013/03/chrome-web-store-and-unsupported.html
It is one time activity to install it on your domain using a PC. Once this is done, you can access the app and its administration on your mobile phones..