Hello Theo,
We're sorry to hear you're having trouble.
To rule it out, quit out of InDesign and then try updating both your versions of Adobe Air (from here: https://get.adobe.com/air/) and Adobe Flash (from here: https://get.adobe.com/flashplayer/) and let us know if that helps once relaunching InDesign and trying again afterward.
If not at first, please redownload the tools again from our website (here: https://www.magplus.com/my-magplus/ after logging in with your credentials) and see if that works as well.