My Mac pro won't let a pop-up I need open.

You usually need to specifically turn on the ability to display pop-ups in browsers in each browser:

1. Allow or block pop-ups in Safari on Mac - Apple Support
2. Firefox: https://support.mozilla.org/en-US/kb/pop-blocker-settings-exceptions-troubleshooting
3. Chrome: https://support.google.com/chrome/answer/95472?hl=en&co=GENIE.Platform%3DDesktop

suejw21 wrote:

https://discussions.apple.com/content/attachment/5f692c9a-6539-4307-9974-5a8506c03306

That seems more a server side embedded "link" within the site than a pop-up...(?)

Did you contact the site owner/support if you do not have access.

Did you try a different browser to compare your results.

suejw21 wrote:

I disabled my ad blocker, cleared the browser data, and restarted multiple times, and I am out of ideas. I'm mainly on FireFox, but I tried Safari and Chrome, and none worked. Any suggestions would be appreciated!

Maybe if you share what exactly is this pop up(?) that you need open would be helpful here.