also, if you are using MSVC you have to tell cmake to generate makefiles instead of project files. Pass the -G "NMake Makefiles" arguments to your cmake call
You sir, have saved me. I can't believe they don't specify that in the guide (it also uses MSVC, so idk why there wasn't the same problem).
I've run into some trouble while building, but that can/should be its own topic.
Slightly related, is QCA supported and updated? The last thing you'd want is to use an out of date cryptographic library.
I normally use Crypto++ but libcrypto of OpenSSL is also very good (if you don't mind messing with C)
It is still active, looking at the the git (https://cgit.kde.org/qca.git/) the last commit was in 2017-09-30 (some months ago, but it isn't dead).
I had also been looking at Crypto++, but ended up settleing for QCA for no pacticular reasons. And I wouldn't mess with C, I'm still even just a C++ newbie afterall ;) QCA can also use OpenSSL btw.