Unblock website on MacBook with pop-up blocker

Here you go:

Allow or block pop-ups in Safari on Mac - Apple Support

Also there is a Shortcut when you are on a site and the Pop-up is blocked where you can allow it just for that website by clicking on the icon in the left part of the Address Bar and choosing Website Settings. Change the option under Pop-Up Windows. You may also see the option in the right side of the Address Bar to allow the block up each time a request is made. If you are using a third party blocker installed as an Extension to Safari, you will need to refer to any options that they provide.

if this is the built-in pop-up blocker in Safari, that can be selected by web sites in recent MacOS:

Safari > Settings > Websites > Pop-up-Windows > ...

... then specify Allow/Block/Block and Notify for that specific site.

EDIT: Jim Mac ID post was not visible when I started composing. My post is not intended to diminish what they said in any way.

Their method is the quick 'at this moment' way, mine is the more mundane, works for everything way.