Expo如何在Android上以mp3格式共享和保存

我有这两个按钮，它在android模拟器上正常工作。它在mp3中下载和共享，只是在构建中不会发生。下载不会在BIN文件中运行和共享。

async download() {
    const perm = await Permissions.askAsync(Permissions.MEDIA_LIBRARY);
    if (perm.status != "granted") return;

    let url = this.props.sound.uri;
    let path = url.split("/");
    const file_name = path[path.length - 1];
    FileSystem.downloadAsync(url, FileSystem.documentDirectory + file_name)
      .then(async ({ uri }) => {
        await MediaLibrary.createAssetAsync(uri).then((asset) => {
          window.alert("Download complete!");
        });
      })
      .catch((error) => {
        console.error(error);
      });
  }
  async share() {
    let url = this.props.sound.uri;
    let path = url.split("/");
    const file_name = path[path.length - 1];
    console.log(file_name);
    FileSystem.downloadAsync(url, FileSystem.documentDirectory + file_name)
    .then(async ({ uri }) => {
        await Sharing.shareAsync(uri);
      })
      .catch((error) => {
        console.error(error);
      });
  }