I think the docs are a little sparse on this but there are examples in this forum I'm sure. What you do is create the group by clicking the + button on the bottom left of the window
And you'd get a group on the left side, this is just like creating triggers for specific apps but instead for a group with conditions. On the right sidebar then you specify conditions, where you can match window title to check for specific windows. Then just add triggers like you normally would, these would only apply when the condition matches your specified one.