Tried several times, different pc, different Zorro version, following the steps in the manual without success. It's very frustrating and a huge waste of time. Some help is much appreciated, thank you.

Solved.
The problems were my paths to the JDK containing spaces. The default path for installing Java is "C:/Program Files(x86)/Java/jdk1.8.0_151". When I moved it to "C:/Java/jdk1.8.0_151" Dukascopy (and IG) magically appeared in the scrolling menu.
Thanks to Ibne, the plugin developer.