Cumulus depends on the Tagadelic module. Get it from http://drupal.org/project/tagadelic before installing Cumulus. Cumulus also requires a JS script called SWFObject. This script is licensed under the MIT license and can't be hosted on Drupal.org. So, you need to get the file from http://pratul.in/files/cumulus.js OR http://pratulkalia.googlepages.com/cumulus.js and put it in your Cumulus folder in your modules directory.