Upgrading gives error "Invalid Drive Z:\"

I have TeraCopy 3.9.7 installed on Windows 10 in an enterprise environment. My Z: is not a partition; it seems like some kind of tmp folder on my computer. I don't pretend to understand it.

TeraCopy prompts me to download and install the latest version (3.12) and I click through the installer/upgrader and it fails:

Clicking OK here drops the installer out saying it failed for some reason.

I've tried to remove the Z drive, but it's had all sorts of folders and such.