How to download and save PDF,EXCEl,CSV file in device ?

I am using Expo.FileSystem here and I have to download file from my api and save it to my Videos folder in internal storage.

I have to save the file to my videos folder and not in FileSystem.documentDirectory folder.

      FileSystem.documentDirectory + 'sample.pdf'
    ).then(({ uri }) => {
       console.log('Finished downloading to ', uri);
     .catch(error => {

If I put any other location instead of FileSystem.documentDirectory + 'sample.pdf' then it shows this location is not writable. please help...