Box2D Plugin Assistance Needed

[billmo]

I recently purchased the Box2D plugin for phaser and have been playing around with it with some success. I've now moved onto the point where I would like to make some custom polygons but am having trouble finding answers on the easiest way to do this. 

I looked at the Phaser docs and essentially want to do something like the following https://phaser.io/examples/v2/box2d/car-on-terrain. All seems pretty straight forward except for the polygon creation. Where did the vertices come from? How did the flattened xy coordinates come to be? I tried purchasing RUBE but there seems to be nothing that exports like so. Either that, or there just isn't enough helpful information out there regarding integrating RUBE polygons with Phaser. In fact, much of what I have found recently suggests that RUBE doesn't even play well with Phaser anymore. 

If anyone could point me in the right direction, that would be hugely appreciated. At this point, I feel like I wasted my money on the Box2D plugin.