Probably the extension is not compatible with new versions of Inkscape. I don't offer support for this extension anymore since I don't use Inkscape anymore. The code is open source and can be continued by whoever wishes to do so. I can make admin of the repository whoever wishes to continue it. The idea behind it is good, Inkscape yet does not implement pages. The implementation however, is a little old and frankly not that good. I've done this more than 10 years ago.
@coalarchy: I've added you as admin to the project. Please let me know if there is anyhting else that you need. And good luck with continuing this project.
I am not actively maintaining this project anymore. Please note that Inkscape should've...