Can't install plugin - Could not find plugin folder in zip
As Brad mentioned in his comments, make sure you have the latest version of the plugin uploaded to the craft/plugins directory on your production server. I just tried it for testing sake and it seemed to work fine for me! 

If you are sure they are in the right spot, check out this answer from a different question, stating to make sure the directory names are all lowercase, so "downloadassets" and not "downloadAssets" or "DownloadAssets," as many production environments are case-sensitive.