Do not manually unpack the zip. Simply download CB and install the entire zip through Joomla extension manager. Do not attempt to manually install. It will not work correctly. If it will not install then again you have a permissions problem on your server as it's unable to move, unpack the files, or what appears to be in your case unable to override existing files or clean up after it self. See the below topic on Joomla forums regarding your issue; it is not extension specific but a server problem.
forum.joomla.org/viewtopic.php?t=967307
You can check some permissions within System > System Information > Folder Permissions. This won't show chmod permission problems though.