Web Browser Issue: Website opens in FireFox, but not in Opera

Running Linux Mint 20.1 (Cinnamon), when I try to log in to Horizon Blue (https://my.horizonblue.com/home), using Opera, our preferred web browser, a security error message is incurred.

To troubleshoot, I installed the Firefox web browser, and I can log in, with no problem.

I don't want to have to resort to maintaining 2 web browsers. Can I tweak Opera to make it work, and if so, how?

Thanks, guys!