There really isn't more information about this than the above so we don't know.
Here's a few Dutch sources at the bottom you can throw through a translation service: "nearly all windows computers were hacked", "we dont know if this was criminal and if the perpetrator(s) demand money".
Noteworthy quote "We are researching if the attackers could access that. Our expectation is that this is very difficult." on the storage of scientific data.