There are known issues with Adobe Download Assistant:
Known Issues section of Troubleshoot Adobe Download Assistant - http://helpx.adobe.com/creative-suite/kb/troubleshoot-download-assista nt.html#main_Known_issues.
You may alternatively download the products from the following location:
http://prodesigntools.com/adobe-cs6-direct-download-links.html
1) You need to stay on the Adobe trial page for the respective product that you're downloading. You should be signed in.
2) Copy/ Paste Link 1 , Link 2 for the files that you're downloading from Prodesigntools on to the address bar of Adobe trial page and hit enter.