Try "Run as administrator" for the installation program.
Yes, even when logged in as administrator "run as administrator" is different from "run". It's confusing.
I have Windows 10.
While I was installing downloaded Word Processor "LibreOffice's" latest version 5.4.5, a message popped up, saying "Installation cannot continue. Log on as Administrator or contact your system administrator."
Where do I "log on as Administrator" for the above purpose? (I am the only "Administrator" for my stand alone home PC.)
Thank you!

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic