Insteon integration: Where do I enter the USB device path?

I’m trying to test drive the built-in Insteon integration. Currently things are working well via MQTT, but looking to simplify.

When I try to add the Insteon integration, I choose the PLM option, and am presented with this dialogue box:

Where am I supposed to enter my PLM device path? There’s no text field or drop down menu, even when I view the page source.