User Private Files Plugin specific issue

[ Moderator note: moved to Fixing WordPress. ]

I installed a plugin User Private Files from https://github.com/fldtrace/user-private-files-plugin.

This plugin is specially for file upload for specific users. By default, this plugin only support PDF files but with the help of some customization mentioned in “http://www.fldtrace.com/wordpress-user-private-files-plugin” you will be able to add other files.

Once I did some changes txt file started working but not doc and powerpoint.

I tried adding a issue on github but no reply at all.

So, anyone here who can help me fix the plugin.