Gi'day João,
You're using Firefox, huh? ;)
Firefox is extremely aggressive with their Certificate identification process ... well-intentioned but a touch over zealous at times (IMO); yes I have had the *bizland.com error warning too. However, because I have downloaded aircraft & repaints from PAD recently that warning no longer pops up (I had to clear my browser cache just to get it to display that warning again :) ).
Have re-accessed PAD yet again and test downloaded the PAD DHC-6 and a Winair repaint. I use MS Defender and have my firewall up, ... it's not a spoof site, nor have I had a virus warning or signs of any attack upon my firewall.
YMMV, of course.
And yes, you are right to be cautious.
Regards,
Dorian
PS. Great to see Alaskan Winds back in the air again. Still have a Michael Sturm AW repaint of Mike Stone's Goose in my hanger.