I have now been able to install, however, DCS World is not runnig correctly:   
These are my current issues: 
- on a lot of objects, textures are missing 
- after a couple of minutes in a mission, the system will crash and go back to windows   
This is what I did to get it to at least be able to launch the system but with the above problems: 
- copied all files from the "_download" folder into the main folder 
- ran DCS repair - but repair broke off with the following error message during unpacking of files: "P:\dcs\DCS World\_downloads\bin/torrent_test.exe: (5) Zugriff verweigert" [i.e. access denied]. Also such a file "torrent_test.exe" does not exist in the folder.   
I'd highly appreciate any help.