Clicking on the "Image" button in Blender's "Render" panel, is what you need to do. That should start the exporting and render process.
The green section of the screen shot indicates that the exporter correctly exported your scene, so that part seems to have gone OK. However, it looks like the path to the Indigo executable is not fully defined.
In your case it says : /Applications/Indigo 3.2/
You may want to complete it to: /Applications/Indigo 3.2/Indigo.app
Once that is completed Indigo should start up automatically rendering the exported scene. If you can't get it to work, for the time being you can always start Indigo manually and open the exported IGS file through the Indigo UI and see if it at least starts rendering so you have some verification that your scene is exported OK. A bit cumbersome, perhaps but better than nothing
Also, as you seem to have some flat glass panes in your scene you can enable "Glass Acceleration" which will greatly help render speed. Once Indigo fires up, make sure that it is enabled by checking in the Indigo UI in the "Render Settings" panel. If it is not enabled you first need to stop the render to be able to enable it. I've lately had some renders not have it enabled even though it was set in Blender. That may just be me though
Another thing that greatly helps improve rendering times are exit portals. Are you familiar with that technique/feature ?