Android webview downloading pdf, xlsm as html file

Question

I convert my website into an android webview app. Everything is working fine but when I am trying to download any file from my website the file is downloading in HTML format. But the files were downloading in correct format when I tried to download from a pc or mobile browser.

webView.setDownloadListener(new DownloadListener() {
        @Override
        public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype, long contentLength) {
            DownloadManager.Request myRequest = new DownloadManager.Request(Uri.parse(url));
            myRequest.allowScanningByMediaScanner();
            myRequest.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);

            DownloadManager myManager = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
            Objects.requireNonNull(myManager).enqueue(myRequest);
            Toast.makeText(MainActivity.this,"Download Started....", Toast.LENGTH_SHORT).show();
        }
    }