Mac reports "Downlevel TV-Quick Support" in error


Today I tried to connect to a friend's Mac which is running MacOS 10.9 Mavericks.
I talked her through downloading the Tv.QS from the web page and then talked her through starting up the App.  Partner ID appeared and was handed over.

When I try to connect I get the pop-up stating that the User is running a downlevel version of TvQS and should upgrade.  I'm running Tv 15.4.8332 on a WIndoze 10 platform.

I next tried to connect to my daughter's Mac running MacOS 10.14: Mojave (again getting her to download TvQS as hers is a virgin 4 day old laptop ! Ok for some) and this worked fine.

Does anybody have any previous experiance of this?
I've trawled through the various forums and blogs but can't find anything similar.

Thanks in advance.