Bonjour Manpreet kaur,

Having checked the audio, it is 'pour' that is used and not 'au'. Sometimes when French is spoken quickly we "blend letters" making some letters unnoticed. To a native speaker, it does sound like 'pour' (even if a little bit "blended" as I explained above). The more you practice your listening skills the better you'll get at recognising words and expressions that might not be as noticeable to an "untrained" ear. See link here: Listening tips

I hope this is helpful.

Bonne journée !