No, if you install the app just for the user who is logged in then you don't need elevated permissions to install or upgrade.
I'm guessing this thing is probably exposed via WebDAV.
edited a bit for clarity.
The easiest way to see this is to use subst to map a drive and then try to navigate to that drive from a UAC-elevated command line. (You won't see the drive since it exists in a different session.)
Mapped network drives and drives shared over remote desktop are other examples of per-user mounts.