Big Cartel Plugin by Tonka Park: problem making it work

I am tryig and failing so far to make the plugin work. I have installed it (at east the steps 1-3, couldnt find how to make step4), but seems to have missed something as my bigcartel shop and the blog dont seem to be connected. Eg. when I tried to install the widget, instead of showing the pics of my products there are the icons you get when there it is not working and the links don`t work as well (Message: The requested URL was not found on this server.).
Can anyone help me with my issue?
Thanks!