I can not find the plug-in for Illustrator or Photoshop. Can you say how it's installed?
I don't think there is a Garmen Creator plug-in for Illustrator or Photoshop. I've checked the Epson website to see exactly what are the available downloading options and the only thing is the actual application developed in Adobe AIR. You can download the software through the following link posted below. Just make sure to select the proper operating system that you currently have installed on your PC, before downloading the application or you might encounter errors when you'll install it.
The software is listed in the Utilities tab.