It's that no one ever, *ever* does this. They took my thirty bucks, sent me a Dropbox link to the Encyclopaedia of Chess Endings II Rooks I (after literally half a day) and it doesn't install, and they *know* it doesn't install. But they keep selling it.
I seriously worshipped the ground that Chess Informant walked on. To be perfectly honest, I still do. Their work is unparalleled. But who does this?
No company should be selling software that they know doesn't install. I'm sorry. This is what they just said to me: "The license key is operational. However, if you’re using Win10 OS it may take a few attempts for installation to finalize. Just repeat the process."