Charity or something else?

I've been living in Iceland for a few months, but this never happened to me, and if it was where I used to live, it would be quite weird

So yesterday night, a man in his 60s knocked at my door and the neighbour's as well asking for a donation for kids with Down syndrome, but it was at 10 at night, and that makes me suspicious

Is it normal here, or should I be worried about something? Have there been cases of scams or other things here?