why is this rar damaged always? how can i download this properly?
The file is NOT damaged. I just tested it.
A corrupt download is rare. There is probably another explanation for your problem.
Your anti-virus app may have has blocked, deleted or quarantined something during or after the download.
It is also possible that the app you are using to unpack an archive is causing problems. Use a trustworthy app like 7zip, Winzip or Winrar. Make sure that you have the latest version.
For a torrent download, corruption is almost impossible. The error detection in the bittorrent protocol is very robust. If your torrent client says that a download has completed than you can believe it.
A direct download from a file hosting site is also likely to be reliable. But if you think that you have a problem with a hosting site then you could download twice and compare the two downloads. If they are the same then they are probably not corrupt.