Remotely registering mobile devices for use on an intranet

[Isaikia]

Hi All.  Completely new to this but have a specific challenge which I think pfSense + Captive Portal + RADIUS (MAC Authentication) might be the answer to.  Just want to see if I have got things right before I even start to move anywhere with it!
What I want to be able to do is for a remote user to be able to log in to a website on their mobile phone using an id+other criteria (in the same way as remotely checking in for a flight for example).  At this point we ask them if they would like to register the device they are using to be able to use on our Wi-Fi when they arrive on site.  When they arrive on site, join our Wi-Fi hotspot and open their web browser we would automatically know who they are and direct them to a specific set of web applications on the local network.
Hope that makes sense.  Am I right in thinking that with the combination of described technologies + an SQL database and other apps that this is potentially achievable, or am I misunderstanding the capabilities of pfSense??