What can I do if Safari pop-ups are blocked?

I have allowed a pop up but it's not opening / allowing a website I need?

Had issues with Safari including this one about a month a go which is why I use Chrome as my main browser now, but I need this browser as a back up and the pop up issue is back....

Before I toggled the allow/block/allow, cleared cookies and cache and relaunched Safari and it worked but this time nothing is fixing it?

[Re-Titled by Moderator]