Haha, you found the right person to help you solve it. I hope you can get online and solve it for you right away. The window "Choose my certificate to sign" is necessary because you didn't download the certificate of Taobao Alipay. If you download it, you must remember where to put it, because when you pay, he will prompt you to enter the password of the certificate, and this certificate should be designed by yourself. If you said you downloaded it and couldn't find it, you might as well look in my folder on your computer. If you say you can't find it, you have to back it up again, which is also very simple. Can you understand what I said? If you don't understand what I mean, if you are online now, you can give me the information right away. Thank you!