What difficulties might arise when adding sound to a web page, node.js?

I am a beginner web developer. Storage: Local storage does not scale. Needs to be implemented using the Web Audio API. Loading indication, caching, and low quality fallback are needed. Architectural challenges in Node.js?

Loading indication, caching, and low quality fallback are needed. Will there be large media files? Local storage does not scale- S3 and Cloudinary for storage, and a CDN for fast delivery.

I don’t know the audio file sizes yet; the client didn’t specify. Here’s the page https://russpuss.ru/podolsk/medlen-18966/ where they’re supposed to be, but I don’t think they’ll be big. What about audio conversion and processing (FFmpeg, Lame)? These are CPU-intensive operations.