React Native. MP3 Binary String (Uint8Array(9549)) to stream or file

I am trying to play an audio file with binary string format that Amazon Polly returns. For that, I am using 'react-native-fetch-blob' and reading a stream, but just keep getting errors from the bridge saying 'Invalid data message - all must be length: 8'. It happens when I try to open the stream: ifstream.open()

This is the code:

//polly config
const params = {
    LexiconNames: [], 
    OutputFormat: "mp3", 
    SampleRate: "8000", 
    Text: "All Gaul is divided into three parts", 
    TextType: "text", 
    VoiceId: "Joanna"
};

Polly.synthesizeSpeech(params, function(err, data) {
    let _data = "";
    RNFetchBlob.fs.readStream(
        // file path
        data.AudioStream,
        // encoding, should be one of `base64`, `utf8`, `ascii`
        'ascii'
    )
    .then((ifstream) => {
        ifstream.open()
        ifstream.onData((chunk) => {
            _data += chunk
        })
        ifstream.onError((err) => {
            console.log('oops', err.toString())
        })
        ifstream.onEnd(() => {  
            //pasing _data to streaming player or normal audio player
            ReactNativeAudioStreaming.play(_data, {showIniOSMediaCenter: true, showInAndroidNotifications: true});
        })  
    })
}); 

Another solution I have also tried is to save the stream into a file to load it later on, but I got similars bugs. RNFetchBlob.fs.createFile("myfile.mp3", dataG.AudioStream, 'ascii');

Huge thanks in advance