Linux mint, being based on Ubuntu also shares the same packages (I use Kubuntu). QtCreator is a separate package and doesn't actually install any of the development packages needed as far as I know (it just recommends them). Do sudo apt install qtbase5-dev qt5-default qtdeclarative5-dev, you won't be able to see the kit right away, go to Tools -> Options -> Build & Run -> Qt Versions -> Add Kit add /usr/bin/qmake which should link to qmake qt5. A list of Qt5 dev packages and their respective modules.