I run with full admin privileges. There is no security software or any restrictions which may be interfering with the installation files being written to the temporary directory.
I really think this below is the problem: on Adobes server there is a wrong manifest.xml file:
See my previous entry: have another look at the line:
<validation_data>https://ccmdls.adobe.com/AdobeProducts/KCCC/1/osx10/packages/ACCC_2_9_PDIMPackage_465//val idation.xml</validation_data>
At the end there are 2 slashes instead of one. That must be wrong, and might be why the installer can't find it. Have you looked at that?