I mean, I honestly don’t know that your OpenCV setup isn’t right. I would expect that if you want to use Qt APIs from within your OpenCV code, you’d need to build with both Qt and OpenCV — I wouldn’t expect that OpenCV would somehow “incorporate” Qt.
(Quite the opposite — if anything I can see OpenCV building/installing some Qt plugins, perhaps, since Qt has an extremely extensible design. And in fact, some docs about the “marriage” of the two mention integrating OpenCV into QtCreator, which makes sense.)
Given that you have QtCreator installed, I’d suggest trying to get your code building in there, sice it basically guarantees that you’ll at least have the Qt dependencies available. (Working in OpenCV, that should be a lesser challenge.)
There also may be example projects ready-made that you could try to build, to verify the install. (Certainly, there are tons of example projects available in Creator, just to confirm that Qt itself is sane and functional.)