How did the Alberta electoral list get leaked to the Alberta separatists?

So I’m seeing some news (like this) saying that a database containing private information about Albertan voters got leaked to the Alberta separatists? And then the separatists made it into a searchable, public database? News outlets generally seem averse to speculation so none of them touch on how this happened.

So that’s my question: how could something like this happen? What went down?