Either the URL you are requesting does not support a
GET
request; or you are missing required parameters from your request; or you've hit one of those sites that doesn't work without
a "user agent" header[
^] set"; or there is something else wrong with the request.
Nobody here can help you. We don't have access to the code running on the site you're trying to download from.
You will need to contact the site admins to determine whether what you are trying to do is possible, and what the cause of the error is. We cannot do that for you.