Electronic patent applications can't be submitted, and digital certificates can't be downloaded.

Try another browser. You can try the IE browser that comes with your computer first. If it doesn't work, you can download a sogou or qq browser and try it. Sometimes the browser doesn't support it or it is blocked.

It's very likely that IE browser has blocked the plug-in. You should reopen it and then submit it. See if there is a prompt above or below IE browser to block the plug-in. If there is, you can just click Allow it directly.