If you desire to respond, I would relate the topic to her field. She claims to be a photographer. Surely she has a vague idea of copyright law. I would explain that you had developed a piece of Intellectual Property and licensed said property in a specific form -akin to taking a photograph. The person who takes a photograph owns the copyright. It just so happens that Spotify and Instagram, "enjoy your work" and have decided to make use of your work under the license you have given.