You need a QPA to build a standard Qt application. The stock one is *not* usable as such.
The sanest choice right now is probably the one from
UMR, but I have no idea how solid the Libra 2 support is.
TL;DR: Don't expect a plug'n play experience, you'll need a solid Qt5/embedded/x-compilation background in order not to run around in circles like a headless chicken.