sorry, danielsan, you're waisting your time.
that cmake documentation is a very interesting read but it is not what is helping you compiling scribus from source.
the package and all the files in there are correct (or at least you have not proved the contrary until now!) and debian testing *can* compile scribus 1.5 without needing to pull in any external (as not from the provided packages) code.
what you need is to figure out which packages you are missing.
for the cmake command, if you use the one i mentioned in the previous post, it should work.
if you use the one you mentioned in one of your first posts, then it should work, too... even if you will have your scribus in an uncommon place (and not the best one, for my taste)
if it does not work, it means that you are missing some -dev packages.
since you don't want or cannot provide the list of packages you have installed during your tries to get scribus to work, please check at least if qtbase5-dev is installed... since the error seems to be pretty basic and qt5 does not get installed when pulling in the dependencies for the stable scribus.