Azure Active Directory Sync Tool DirSync Fails

I am trying to sync the local AD with Azure.

Unfortunately it won't let me and tells me that the username/password is wrong.

GetAuthState() fehlgeschlagen mit -2147186688-Status. HResult: 0. Wenden Sie sich an den technischen Support. (0x80048821)

Which username/password should I enter? I tried the one that let's me access Azure as administrator. The account I use there ia a Microsoft Account, not an organizational account.

I already tried to follow support.microsoft.com/de-de/kb/2517393 with no success.

Thanks!