I found that and emailed a request but haven't heard back. They emphasize sharing info on that site. If you want something you have to provide something, and more specifically, if you want a set of plans you need to supply a set of plans. Unfortunately I only have one other Sterling kit, the Waco SRE, and they already have the plans for that.
I own a CNC router and this summer/fall as I build the Waco SRE kit I will be drawing all the parts in CAD, so that some time down the line I can build a larger 72" wingspan version. I offered those drawing, when finished, also. We'll see if they are interested.