This guide will provide information on how to set up a SiteManager so you can get a connection to the internet through a Captive Portal, and the downsides by connecting a SiteManager in the way.
The issue with Captive Portals is that every time the session expires where the SiteManager is connected, or the SiteManager is rebooted you would need to log in manually and log into the Captive portal again and grant access.
This would work if you are at a hotel or showing off the SiteManagers capabilities. But if you have the SiteManager in a production environment then you would need a man onsite whenever the SiteManager loses connection. (This can be every day in some cases.)
A better solution is to contact the IT department and open up so the SiteManager does not get captured by the website when trying to access the internet. The ports needed in order for the SiteManager to communicate with the GateManager is: 80,443 and 11444. For more information please see: SiteManager - Connection requirements
If you need to enable access through a Wifi network where you need to login on a web page, then you would need to put your computer on the DEV port of the SiteManager, create a Scada agent to the computer, and login on the website with the computer.