The ISO format does not support Audio CD. So, it seems your ISO is not an Audio CD ISO.
powerdvd does not support to mount or open a "data disc ISO", which stores audio files, as powerdvd is not a ISO utility.
However, Windows 10 can directly mount ISO in a virtual disc drive, then you can browse the audio files in Windows file explorer directly.
Blu-ray audio or DVD-Audio disc is not supported by powerdvd.
So, what disc type is your ISO?