To be able to have auto updates, you will have to validate your theme installation.
To do this, please follow the steps on this link:
Once you are able to validate your installation, you should be able to get the automatic updates. However, please note that automatic updates does not mean the plugins and X will update by themselves when there is a new release. It means that you will be able to get the update notification and be able to do the update from the dashboard in few clicks rather than manually updating through FTP.
Hope this explains it.