How do i fix this download error 2503

Downloaded latest UnrealEngineInstaller.msi to desktop Win 8.1, 6 gigs of RAM, Nvidia 760 Trying to install to "C:\Program Files\Unreal Engine" (an SSD drive)

“The installer has encountered an unexpected error installing this package. This may indicate a problem with this package. The error code is 2503.”

Closing that box I immediately get:

“The installer has encountered an unexpected error installing this package. This may indicate a problem with this package. The error code is 2503.” Then the installer only gives me a FINISH button. So kinda stuck.

I also tried redownloading in the hopes the first .msi was corrupted