Audio Library and using S3

I have created a website in WordPress which includes an audio library of 45- 50 minute talks. This is going well. I have an idea of making the audio library an app to listen to and take offline. The website already allows downloads but an app will keep everything together on the device.
I have thought about moving the audio to AWS S3 and then I have seen I could use the AWS Amplify library to stream to an app (perhaps using React Native). Will this be a cost effective way or could I just stream from the current website where the audio is currently stored? Do you have any suggestions of how to build the app? I love JavaScript and React Native.

Thanks in advance.