To add to Guillaume's comments, when we say "in general, planes from X-Plane 10 will work with X-Plane 11" we specifically mean "planes updated for X-Plane 10.30 and later."
I checked out this specific plane, and it was created for an older version of X-Plane. You may be able to get it to work by opening it in the latest Plane Maker for X-Plane 10, saving it, then trying it again in X-Plane 11.