Reconsider your solution.
As you already said :
@carzin:
If they go to google or any other http site, it works just fine. The redirect happens immediately.
So why adding google.com to the 'allowed site' list ?
Check this https://forum.pfsense.org/index.php?topic=115338.msg644308#msg644308
Most OS's will open a navigator by default "automatically" when a Wifi connections comes UP (obtained an IP, gateway, DNS, etc) and the direct "Internet connections" (with a test http call). No end user interaction needed.
Check this :
@carzin:
For whatever reason, if they type wifi.sitex.edu, the browser will spin and spin and will not connect them to the authentication portal.
Where is "wifi.sitex.edu" ? Is it the URL being served by pfSense or elsewhere ? If it's the latter, it should be added to the 'allowed site' list.
Check also if "wifi.sitex.edu" is including pages from other locations (Google analytics, etc) because this will block the loading of the page (your "spinning around").