If you need it in mp3 format specifically you might need to do some transcoding because some shows/platforms only provide m4a downloads. If you're just interested in the raw audio file you should be able to extract the download links from the rss feed. On the off chance that there isn't a raw rss link available (eg. there's only a link to apple podcasts page), there are guides that allow you to extract the raw rss link via api.