Potential issues to consider: Large file sizes could lead to longer download times and higher bandwidth usage. Implementing progressive download or adaptive bitrate streaming might help, but for straightforward downloads, just making sure the server is optimized.
User Management: If it's a subscription-based model, user accounts are necessary. But since it's a feature to develop, maybe start with an anonymous download option with a limit on the number of downloads per IP or device.
Storage options: Storing the actual media files could be done using cloud storage like AWS S3 or Google Cloud Storage for scalability. The frontend would request the file from the backend, which then streams it from the cloud storage.
Security: Ensuring that the download links are secure, using HTTPS, and protecting against hotlinking. Maybe using signed URLs that expire after a certain time if users need to authenticate via API keys or OAuth tokens.
In that case, maybe focus on features like rate limiting downloads per user, IP-based throttling, and ensuring that the server can handle the traffic. Also, optimizing file delivery with a CDN would be crucial.