I'm working on making a client's blog site AMP-friendly and I'm running into an issue with their audio posts. It's just a simple WP site where they are uploading the audio files for the podcasts and I'm running into an issue where it says
Source must start with "https://" or "//" or be relative and served from either https or from localhost.
I don't see anywhere in their documentation that this is a rule. I have not run into this issue with other media types. Is there a fix other than setting up an SSL for the site?