Current state of the discussion with Autodesk ADN:
a) With "secureload=0" it does the download without problems.
b) With "secureload=1" you have to add the URL to "Trusteddomains" and it should(!) download
But...
there is a problem in current versions, different to older versions: "b)" does not work, and the only solution is "secureload=0". This is logged as Change Request for Autodesk Devs.