The free tiers always have audio length restrictions. Nonetheless, Google NotebookLM is currently free, wherein you create a new notebook and upload your 2 hour podcast (or even its transcript), and it will get the data analyzed and then it will provide a summary. Then, you will have to prompt it to "create a mind map outline of this audio".
But, mapify.so is better, as it uses GPT-4/Gemini to summarize audio and automatically structure it into a visual mind map. It is free to try, but will need one of the premium plan(s) for longer audio files. Their premium plans are not expensive, though.