Can't run Kies 3 - Can't install Smart Switch

[AC Question]

I have a delicate problem... It turns out I neither can run Kies 3 (error message: use Smart Switch instead) nor install Smart Switch (error message: cannot start application because its side by side configuration is false) (free translation from Swedish).

So, how to go from here? I guess Smart Switch is the application to use for the future, but why this error message at the installation?

I am using Win 10 x64.

Thanks for any help!