Unkalibriert: Before beginning the installation process, all Parts of the game need to be downloaded and placed in the same folder.
I've attached a view of my download folder for main game files, the newest patch and the german language pack (which you obviously don't need).
If you have the first ten files on that picture in your download folder, start the installation via double click on the executable
setup_the_witcher_3_wild_hunt_2.0.0.40.exe.
The .bin files are split parts of the installation archive, by the way and must be there or the installation will ask for the path where the parts are placed at (which is the notification you've got).
The reason to split up the installer would be decreased file sizes for downloads, I suppose. It is more troubling if you have to re-download a single 27 GiB file instead of a single one out of six 4 GiB files, one 3.2 GiB file and a 24 MiB executable, in case your internet connection fails at one point.
Thanks, but I see four parts to that patch. Is that...correct?