Thanks for the reply, @SGaist
I have managed to recover a bookmark with the project page - so lucky, but unlucky as well... The project is dead, and only offers Qt builds up to version 5.5.
If anyone is interested, the project page is here:
So now I'm definitely looking for alternatives... If anyone has any suggestions, it would be awesome.
Also, in the meantime, I'm looking forward into compiling Qt myself, but my poor i5-4690 CPU is going to take forever and I'd like to avoid doing that...