How to find the file location of a website’s ssl certificate

I am trying to access the SSL certificate for a certain website (textnow.com) but I can’t find where it is stored on my computer, even in the certificate manager.
Also, when I click on the lock next to the website name, then connection is secure, then certificate is valid, I see this:

The view certificate button is greyed out and it doesn’t let me click it. How can I get the local file address of the certificate?