How to fetch FileStreamResult from API on React JS

Question

I have dotnet core API return a FileStreamResult, but my React app does not get the response.data expected. I have tested the API on Postman and it brings the 200 with pdf OK. See my code:

API

 [HttpPost]
 [Route("downloadFile/{fileName}")]
 public async Task<IActionResult> DownloadDoc(string fileName)
 {
   BlobServiceClient blobServiceClient = new BlobServiceClient(_storedconnectionString);
   var container = blobServiceClient.GetBlobContainerClient(_azureContainerName);
   var isExist = await container.ExistsAsync();

   if (!isExist)
   {
    //Create new container
     await container.CreateIfNotExistsAsync();
   }

   var blob = container.GetBlobClient(fileName);
   if (await blob.ExistsAsync())
   {
      var a = await blob.DownloadAsync();
      return File(a.Value.Content, a.ContentType, fileName);
   }
   return BadRequest();
}

REACT

export async function API_DownloadDoc(fileName){
  const access_token = Cookies.get('access_token')
  const requestOptions = {
    method: "POST",
    mode: 'cors',
    headers: {
        'Authorization': `Bearer ${access_token}`,
        'Content-Type': 'application/json'
      },
      responseType: 'blob',
    }

  return await fetch(`${config.apiUrl}api/downloadFile/${fileName}`, 
  requestOptions).then(async (response) => {
        const isJsonBlob = (data) => data instanceof Blob && data.type === 
        "application/json"
        const responseData = isJsonBlob(response?.data) ? await (response?.data)?.text() : 
        response?.data || {}
        const responseJson = (typeof responseData === "string") ? JSON.parse(responseData) : 
        responseData;
        return responseJson
  })
  .catch((error) => {
    return error
  })
}

Response I Get

body: (...)
bodyUsed: false
headers: Headers {}
ok: true
redirected: false
status: 200
statusText: ""
type: "cors"
url: https://localhost:55000/api/case/downloadDoc/file.pdf
[[Prototype]]: Response

I need the response on blob format. I would appreciate any feedback, thanks.