I just loaded the plugin and got the same message. After a little look at the file feedlist.php the first lines try to establish the Wrodpress installation folder but this is hardcoded!!! Not great programming.
my installation for example is http://www.mysite.com/wordpress so i've had to change the line to read...
// include files
$relroot = dirname(__FILE__).'/../../';
which is the plugin folder plus 2 folders up in my case to get to the wordpress root folder.
You'll need to amend that initial bit to what you require.
Hope that helps.