How to trigger task when Play/Pause button is pressed on Podcast Addict widget or notification? I would like to trigger a task when the Play/Pause button is pressed on the Podcast Addict widget or notification on lock screen.

I've tried using Receive Intent but that's not working (possibly because the intent itself isn't broadcast).
You can't do it this way. Buttons on widgets are signalled via intents, that's true, but the intent is delivered only to the app that owns the widget - in this case, Podcast Addict.

Instead, you should create a button widget through Tasker, and have it trigger a profile which does the other stuff you want and sends the same intent to Podcast Addict that its own widget would send.