Expired Certificate Issue

I see that this issue has occurred for other clubs and hope this doesn't count as a duplicate ticket. I'm not very technical and wasn't able to understand most of the responses. We don't have anyone who actively manages the technical stuff and I seem to have inherited it by default as the current president. When trying to access www.renotoastmasters.com I get a pop up warning that the site may not be secure and had to manually accept the certificate (or something?). Other members have had the same issue.

This is for Washoe Express, club 456. Another member did just inform me that they were able to access the site without issue. Hopefully someone can advise on how to proceed.

What operating system and Browser and version are you using?
If an apple product use the Fire Fox browser until a patch is issued.

Thank you. I'm using Apple 10.15.7 and Safari 14.1.1 but other members are using various browsers and also having the same issue. I'll notify them to use Firefox in the meantime. Is there action that I or anyone in the club need to take or is this resolved by... someone else? As I said, I honestly don't know how any of the back-end stuff works for our website...

Edit: In the meantime, there is the option to ignore the warning and still continue to the site. Is there any actual risk to this for members? Can I advise them that it's a technical issue and not a hack so they're ok to just proceed past the warning?

Same for us on Apple Safari and Chrome: bwtoastmasters.com
club 4735 
Our certificate expires in Nov 2021 but it shows as expired.

Use Firefox it will work as it has its own Cert repository.
Safari and Chrome rely on the Apple OS repository

We have applied a patch to work around Apple's issues.

Please try your sites now.