The notation "This product cannot be launched directly" means the product cannot run from inside the Command Center. AFAIK, the only products that may be launched from inside the Command Center are Cakewalk DAWs. None of the synths may be run from the Command Center. This has nothing to do with installation though.
Are you receiving any error messaged from the Command Center?
What does the installer do when you run it manually?
Have you tried verifying the manual download using the md5 hash supplied on the download page?