XC uses Qt just like Lazarus uses Qt. Qute apps generated are dependent on the Qt Framework libraries.
If you download XC, just create a new project using the Qute Cross Framework, then add components and code, when you compile, the generated exe will use the included QT Framework DLL's and libqt4pas bridge just like in Lazarus.
On Windows you would have to deploy the Qt dlls with your exe
On Linux your apps Qt libraries and bridge can be installed via repository
On Mac just install the Qt packages included in the XC installation along with your app
Qt 4.8.5 was an upgrade on Windows.
In a Qute Application you can for example use styling.
App.QuteStyle('Plastique');
for example.
PS: I don't want to discourage you but if you plan to write a standallone app you might want to stick to Lazarus, cause XC is designed for Grid Computing and distributed modules, I mean you could use it but it would not really serve its purpose.