This site put it password protected recently. I don't really know why.
If you want to search for papers though you can use google. On each paper there is a code on the top of it. For example to this is a chemistry standard level paper 2.To search for it:
N10/4/CHEMI/SP2/ENG/TZ0/XX
N10 - is the month and the year
4 - is the subject the group is in
CHEMI - is the subject
SP2 - is standard paper 2
ENG - is the language - english
TZO - Timezone
And for markscheme its N10/4/CHEMI/SP2/ENG/TZ0/XX/M (where m means mark scheme)
So you can just manipulate the code to what you want and usually you get the paper.