Audio source url link

How do I know the URL link for an audio file?
When going into the alexa development console and look at the json output console, it looks like this:
But in Voiceflow Speech Block it is difficult to batch with API because some of the following characters are missing:

Changing file properties with audacity app and uploading audio files using Amazon s3 resolves the problem. I’ve been doing voiceflow with programming beginners, and I’ve learned a lot in a month and a half. Thank you for your help, voiceflow officials.