I am unable to get audio/video URL on my callback. I just get a random ID in the incoming payload

Use the below API to get the media payload:

curl -X GET \ https://api.gupshup.io/sm/api/wamedia/{WhatsApp-App-name}/{VoiceID} \ 
	-H 'apikey: {Gupshup-Account-APIkey}'

Response type will be: application/octet-stream