Xfinity Stream App on Google Chromecast Device - Does it Work?

​I have sideloaded the Xfinity Stream App '.apk' file (version 7.1.0.026) onto my chromecast dongle.  I loaded the app and it does not show in the 'App" list.  I see the Xfinity Steam App when I go to 'Settings - All apps".  I have set the permissions to "Allow".  I can Open the Xfinity Stream from this list which takes me to a 'Sign In' screen but when I select the 'Sign In' I get the message "You don't have an app that can do this".  Is it not possible to have the Chromecast unit run the Xfinfity Stream app? ​