Chatter Desktop and Communities
|Knowledge Article Number||000222100|
|Description||Users are unable to connect Chatter Desktop with their Communities.|
|Resolution||Chatter Desktop does not support Communities at this point. Currently, users can only connect Chatter Desktop to their production or sandbox orgs. See this for more details on connecting Chatter Desktop. Note to connect Chatter Desktop, the login url must end with *.salesforce.com. And most Communities orgs use *.force.com.
As an alternative, users can use Salesforce1 mobile app to access their Communities. More on that here.