@Tau_Hopper Unfortunately, Ubuntu 14.04 is not the supported Ubuntu platform on QT from 5.9 forwards: https://doc.qt.io/qt-5.11/supported-platforms-and-configurations.html
I have to compile QT from source due to problems making sure QT’s proto’s and ours are compiled with the same version of protoc. I haven’t tried compiling QT5.11 from source on 14.04 but given that it’s no longer the supported Ubuntu platform and falls under the generic “linux” platform umbrella, I see that as a route of pain.
I don’t suppose I can convince you to run a do-release-upgrade? Otherwise in your case I would suggest either running the windows launcher under wine or using steamplay.