In order to read your book on an Android device, you will need either Mantano or Aldiko v.2.0, which support Adobe DRM. They are both available free from the Android market. If your device came pre-loaded with one of these apps, be sure to upgrade to the latest version if you have not already done so, and authorise the app to the same Adobe account you've used to purchase books. For more information about authorising Aldiko with an Adobe ID, please take a look here: http://aldiko.zendesk.com/entries/368907-authorize-device-with-an-adobe-id You'll find information about authorising Mantano in the Mantano user guide.
If you get an error message when you try to authorize your device to your Adobe ID, please contact the support for the application you are using directly, or Adobe support, who will better be able to assist you with the resolution of your problem. Feedbooks support can only provide limited support for third-party applications and Adobe authorization.