A customer is configuring on an old desktop an inexpensive file server to share photos...

For an inexpensive file server to share photos and videos while avoiding complicated licensing, the technician should recommend:

Linux: Linux is a free and open-source operating system that is ideal for setting up a file server. It offers robust file-sharing capabilities with minimal licensing complications.

Chrome OS: Designed primarily for lightweight, web-based tasks and not ideal for a file server.

macOS: Requires Apple hardware and involves more complex licensing compared to Linux.

Windows: While capable of being a file server, Windows may involve licensing fees, particularly for server editions.