how to open files from android download manager's notification in react native android?

Question

I am trying to open pdf files which gets downloaded through the android download manager in react native . I have used rn-fetch-blob for this and I think am unable to set the path in the download manager... here is code for it ... tried opening files from the notifications but was not able to do so , every time i clicked on the "file downloaded successfully notification" got an toast error saying "Can't open file".

const downloadFile = fileUrl => {
  let date = new Date();
  let FILE_URL = fileUrl;
  let file_ext = getFileExtention(FILE_URL);
  file_ext = '.' + file_ext[0];
  const {config, fs} = RNFetchBlob;
  let RootDir = fs.dirs.DownloadDir;
  let options = {
    fileCache: true,
    addAndroidDownloads: {
      path:
        RootDir +
        '/file_' +
        Math.floor(date.getTime() + date.getSeconds() / 2) +
        file_ext,
      description: 'downloading file...',
      notification: true,
      useDownloadManager: true,
    },
  };
  config(options)
    .fetch('GET', FILE_URL)
    .then(res => {
      console.log('res -> ', JSON.stringify(res));
    });
};