RPi0W dtoverlay for pwm audio

Hi,

Running latest dietpi on raspberry pi zero w.

Tried to get audio through pwm as per below link
https://www.tinkernut.com/2017/04/adding-audio-output-raspberry-pi-zero-tinkernut-workbench/

But playing audio (.wav) says no file.

root@DietPi:/mnt/dietpi_userdata/Music# ls
hey.wav pink.wav song.mp3
root@DietPi:/mnt/dietpi_userdata/Music# aplay hey.wav
aplay: main:828: audio open error: No such file or directory

Tried aplay -l
root@DietPi:/mnt/dietpi_userdata/Music# aplay -l
aplay: device_list:272: no soundcards found…

Searching further found these posts
https://www.raspberrypi.org/forums/viewtopic.php?t=273646#p1776306
https://github.com/raspberrypi/firmware/blob/master/boot/overlays/README
Can you guys guide me to implement it…

pi@raspberrypi:~$ dtoverlay -h audremap
Name:   audremap

Info:   Switches PWM sound output to GPIOs on the 40-pin header

Usage:  dtoverlay=audremap,<param>=<val>

Params:
swap_lr: Reverse the channel allocation, which will also swap the audio jack outputs (default off)

enable_jack: Don't switch off the audio jack output (default off)
        pins_12_13              Select GPIOs 12 & 13 (default)
        pins_18_19              Select GPIOs 18 & 19