That response can be due to older versions macOS, and your OS info is something you did not include in your questsion. Please do "About this Mac..." from your Apple menu to find your macOS version and post it as a response to your question.
Also tell us what browser you are using. We are really bad at guessing.
I suspect, like many other sites, your Uni has been bitten by expired security certificates from one issuer of certs. Since 30 Sept we have seen many posts like yours. I had that warning Wednesday and the site I was trying to access was using certs from the issuer in question.
This is the "Why" posted by the issuer whose name keeps popping up.: https://letsencrypt.org/docs/dst-root-ca-x3-expiration-september-2021/
Your Uni probably need updated certs and you cannot fix that from your end.
If you are using Safari or Chrome browsers, you might try FireFox. People much smarter that I have said FireFox handles certs differently from other browsers.