Problem with Canada Maps app from dubbele.com

I've just purchased and downloaded this app onto my ipad, but it appears not to be working.

It starts up, and shows a map of a bit of Montreal, but I can't move the map (tried all the gestures I can think of), and the (menu?) icon at the top right does nothing.

Has anyone else had a problem with this.

What recourse do I have if it continues not to work?

I'm running iOS 8.2 on an ipad air