I just checked the online installer and it should work as long as nothing is blocking the connection on your end.
PDF Architect contacts the licensing server to make sure the license information is valid. It uses the Internet Explorers proxy settings, so please make sure that they are set up properly.
Please make sure that a request to http://activation.pdfarchitect.org is possible. The requests use the content-type text/xml, in some cases, this might be required to be enabled separately.
I am afraid offline installation packages are currently only available for PDF Architect 6.