ukash virus with a apple popup window

Sorry but xcan;t post to apple supportcommunity, so i post here, not my fault.

This happened on my Ipad
I was on one of 'those' streaming video sites, if you know what I mean.
A well known that lots of people use, so I didn't expect this.

I suddenly got this UKASH/police 'virus'/scam things.

But weird thing is, everybody here that hadit , it was just a webpage. With me the old page was in background and I had a white popupscreen telling me I had to pay this 100 euro fine. I knew it was fake, but what scared me is, that it is the same white box that comes up when apple asks my password like when I purchase an app. how can cyber criminals make this white box appear on my Ipad. Ithought only apple could do that, or am I wrong.

I pressed cancel, and it immediatly came back again, then I tried a few times to press cancel and immediatly close the page pressing the little 'x', after a few tries that worked.

Is my Ipad still safe to use?

I am especially scared because instead of a webpage with the scam it was the white apple box with the scam.