User1771714573 posted
Hi ijuedt,
You can open IIS log to check the sub status code of 401 error.
Usually, SSL certificate will not need password when you access site through https. So you can try to change another certificate. If you test it in development machine and the machine has installed IIS express, you can use certificate of IIS Express. Or
create a new empty site binding to your certificate.

Besides, did you set SSL to require certificate? This is client certificate setting not SSL configuration. So you don't have to set it to require But just leave it as ignore.

Certificate will not ask for username and password and any other thing. It will only show an insecure connection because your client does not trust this certificate, but the request can still reach the site.

Best regards,
Brucz