Have you confirmed that you have all the pre-requistes in place?
Explicitly the MSXML at the exact edition required, etc.
I have just had that 'problem' with a couple of V15 M020 installs on 64 bit PCs where the corporate build for 64 bit didn't have it (made worse because the 'user permissions' did't allow the uninstall of an old component.
If the readme says the old version will be uninstalled, do it yourself to ensure you have a clean start. etc.
Philip