Currently I installed WP plugin 2.11 but unfortunately when I upload a file and include it in a post, download link is not working. I search for the problem so this problem is exist in it from since a long time. I little search about it so I got this news that it was very old free version and the publisher is selling 3.15 version, so it means they are not more interested to fix old version.
Great new is that search over net I found WP-Download Manager it is is providing all that things for free while Download Manger provided in pro version. I am feeling said why I wasted my 4 hours on "Download Manager" while there is nothing special in it.