Klean13 mailing list clean problems

Hello, has anyone else ever had a problem logging onto Klean13? I was advised to use it, but it doesn’t let me login and my browser says the site is corrupted, I have tried on multiple devices.
I’m not sure what to do, their customer support is rubbish.

They have had issues in the past with their security certificate. I’ve stopped using them and started using Zerobounce.