Upload and Download audio files

what is the best way to upload an audio that will be playable in app for everyone? maybe thats not possible, i don’t know.

How large is that audio file? You might want to store it in the assets of your app…

15 to 30 seconds… im asking if is it possible to an user upload an audio to the app and all other users listen to it.

that’s possible.you have to store the files in the Internet, for example your own web server or your Google Drive or Dropbox.
Also you need a server database, for example MySQL to store the file names together with the links to the uploaded files
For details you might want to search the community