Hi Schorsch,
I'm pretty new to the DainApp and not very experienced with debugging but I'll try help. If anyone see's me making an incorrect recommendation please jump in!
What version of DainApp are you trying to run? I assume its the latest 0.4?
Personally, I'm using 0.4 on Windows 10.0.18363.
I've looked at the error "DLL load failed while importing QtCore" and found that when relating to Qt, it seems to be Python3.dll that is native to python installations that may be missing.
Can you search your DainApp folder to see if it contains Python3.dll? Mine has the following: Python3.dll , Python38.dll , Python38com.dll in the main folder. It also has two instances of torch_python.dll in two sub-folder locations.
If its not there, then try downloading and extracting DainApp 0.4 again. To be honest, I'd try re-downloading and extracting again anyway (I use WinRAR).
I hope that gives you some things to try.
Theo