When I installed joomlacomment visualized the same mistake ...
...

There was a problem with your installation



error when moving /home/ascrifo/public_html/administrator/components/com_comment/plugin/joscomment.php

TO /home/ascrifo/public_html/plugins/content/joscomment.php

Please, contact the support.

Thanks.



error when moving /home/ascrifo/public_html/administrator/components/com_comment/plugin/joscomment.xml

TO /home/ascrifo/public_html/plugins/content/joscomment.xml



error when moving /home/ascrifo/public_html/administrator/components/com_comment/plugin/josccleancache.php

TO /home/ascrifo/public_html/plugins/system/josccleancache.php



error when moving /home/ascrifo/public_html/administrator/components/com_comment/plugin/josccleancache.xml

After this error I moved the files that appeared in the error message via the CPANEL and component worked corertamente.
I noticed that there is an almost complete translation for my language is the Portuguese of Brazil, I am available to administrators to help translate, to contact by e-mail.
I hope I have helped someone