The validity of the download links is regularly checked but it might be either you or us.
1) Copy the download URL and try running it with a different browser.
2) Copy the download URL and try it with a different internet connection, if you are a using your internet at work, your connection might be restricted, just try it with your mobile connection.
3) If the above two didn’t work for you it’s shame on us. Just let us know for compensation.