I had exactly the same problem as mycokerewards.
First Steam was installed on C: when I recognised that there is not enough space.
Then tried to install Steam on D: and Steam is not that clever to add a separate folder, hence all Steam-Files were on D:.
Heaving uninstalled D: I got same message. ERROR 1303: THE INSTALLATION HAS INSUFFICIENT PRIVILEGES TO ACCESS THE DIRECTORY...
My solution was go to properties on D: drive. -> tab Security -> add SYSTEM group and ADMINISTRATORS with full access.
Then it workes.