I think that your link might've been hijacked. When I went to the download, I downloaded an iso that seemed to want me to run an installer. Something tells me that this isn't correct for an art pack.
Viewing post in Small Portrait Pack - Arics Compatible
I got it to work with that link, but I had to repeat this cycle a few times: click the link, cancel the bad download(the size of the file usually gives it away), and go back to previous page to click it again. It's a really shitty site that gives you downloads for shit that you don't want and it's slow.