I’m not able to extract article text from that URL because it points to an MP3 audio file, not an HTML page containing written article content.
The instruction you gave—title as H1 and core article text in markdown—applies to web pages with textual articles. An MP3 file does not contain embedded readable article text that can be scraped or converted directly to markdown; it’s just audio data.
If you want, you can:
Czytaj cały artykuł u źródła — Polskie Radio PiK (Pomorza i Kujaw)