Hmm, what is the source of this block? To help figure that out: Could you copy/paste the full message you are seeing when you try to access the site? If the message can't be selected and copied, could you post a screen shot? This article suggests ways to do that: [[How do I create a screenshot of my problem?]] Please cut out or blur any sensitive information in the image before attaching it to your reply.

Is that the red phishing protection window? *https://support.mozilla.org/kb/how-does-phishing-and-malware-protection-work