Hi all,
It looks like OJS was able to download the plugin, but unable to extract it. Are you sure your tar binary is available to OJS and configured in config.inc.php in the tar setting in the cli section? For example:
[cli]
tar = /bin/tar
It seems as though that option is not correctly configured, or PHP is not being allowed to execute it.
Regards,
Alec Smecher
Public Knowledge Project Team