This happens because when you click the "Accept" button on the download page in your browser, the webpage saves a cookie that it uses to check your agreement before letting you download the file. The problem occurs when trying to download from the command line using wget and it's because there's no cookie information sent with the wget request for downloading the file so from the file server's perspective, you're a completely new user who hasn't accepted the license agreement.
One solution is to send cookie information using the --header option of the wget utility (as shown above in other answers). Ideally if some content is protected, you'd use the various session management options available with wget. For this particular problem however, it's solved (currently) by sending the Cookie header with the download request.