First of all, I recommend you download the latest public build (2380) that we just announced yesterday. This has a key feature that helps with plugins and the simulator. You’re running into a problem where the “supportedPlatforms” line is preventing the simulator from downloading a small stub file that the simulator uses to avoid giving you that error.
if you wish to stay with an older build for now, simply comment out the supportedPlatforms line, reload the simulator, let it download the stub, then un-comment the line.
The simulator can’t run these plugins. You have to build for device and test on the device for IAP.
Rob