Phoca Download Component is stored on joomlacode.org server (the download link is an external link to this server, if the file will be not downloaded, please try to visit this link )
Phoca Download plugin files for JComments will be available in JComments since version 188.8.131.52. If you are using JComments earlier version than 184.108.40.206, then you need to copy Phoca Download plugin files (file and category commenting) into your JComments component, into folder:
These plugin files are included in following ZIP file.
Download this file if you need to install Phoca Download via FTP, see Installation Problem Solving article to get more information.