The maintenance tool source is readily available but not useful to solve your problem:
https://wiki.qt.io/Qt-Installer-Framework

In the event that your Linux distro does not package Qt 5 you just need to build the Qt library source on your RPi to get a native Qt library, or build the Qt library using a cross-compiler targeting ARM. Either of these things should be doable with a minimum of fuss.

This forum is not Digia. If you are truly an organisation looking for "hundred of seats" then you should be talking to Digia. A sale that size is good encouragement to help.