OS and version?
Do you have a CC subscription?
"413: Header length too large" is usually a browser-related error and not to do with Adobe or their download servers...
Try clearing your browser cache and trying again. Either that, or try it using another or different web browser.
Hope that helps; please let us know how you make out.
Thanks for the responses, I did try 3 web browsers but still the same. In the end I downloaded the trial version and it is working for now, I will just have to transfer over to the full version soon. Thanks again for the responses.