The plug-in is running in a different window

This dialog box is only there to let you know that the program has successfully launched.  If you do not see your program window, then please look on your task bar for Windows or your dock for Mac. 

The reason we do this, is so that we can launch each plug-in as its own application. The above window is the only thing running in Photoshop as a plug-in. The rest of the program is launched outside of Photoshop. The upside to doing this is that if the plug-in were to crash, it would not crash Photoshop with it.  If it were running as a traditional plug-in, it would likely crash Photoshop whenever the plug-in crashed.