Thanks! Whoo hoo, well, at least partially!
This is what I did: I found a devlibs folder in "build" (under Plasma). It already contained a folder devlibs... which contained a folder debug and libs. The debug folder already contained a folder libs as well. Ok that probably came across as gibberish, so I'll try to created a tree:
The folder ..\Plasma\build\. contains
.\devlibs\debug\lib
and
.\devlibs\lib
So I copied the content .\devlibs\lib to .\devlibs\debug\lib (overwriting a few existing files) and ran the batch again. Now I'm getting:
At least it finished the process now! After that I opened the Plasma.sln file in Visual Studio 17, changed debug to release and selected "Build Solution". That failed and this time I managed to grab the entire log - oh, I can't paste it in one message, so be prepared for LOOONG message next