Download files from a WebView in a Fragment in Android Studio [closed]

I have a project almost finished, which is an official application for the university. The only drawback is that the WebChromeClient does not allow it in the Fragment .

In Main I have this code:

Activity activity = this;
webview.setWebChromeClient(new WebChromeClient() {
    public void onProgressChanged(WebView view, int progress) {
        activity.setProgress(progress * 1000);
    }
});
webview.setWebViewClient(new WebViewClient() {
    public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
        Toast.makeText(activity, "Problemas al descargar archivo. Intente más tarde.  " + description, Toast.LENGTH_SHORT).show();
    }
});
webview.loadUrl(urlWeb);

//descargar archivo
webview.setDownloadListener(new DownloadListener()
{
    public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype, long contentLength) {

        final DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
        request.allowScanningByMediaScanner();

            request.setMimeType(mimetype);
            //------------------------COOKIE------------------------
            String cookies = CookieManager.getInstance().getCookie(url);
            request.addRequestHeader("cookie", cookies);
            //------------------------COOKIE------------------------
            request.addRequestHeader("User-Agent", userAgent);
            request.setDescription("Descargando Archivo...");
            request.setTitle(URLUtil.guessFileName(url, contentDisposition, mimetype));
            request.allowScanningByMediaScanner();
            request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
            request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, URLUtil.guessFileName(url, contentDisposition, mimetype));
            final DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);

            new Thread("Descargar:") {
                public void run() {
                    dm.enqueue(request);
                }
            }.start();
        }
});

In the Manifest I have permission to write in memory, I just need that.