It seems like when you tick the authentication method as Local User Name/Voucher, you don't have a choice, you have to use all 3? Is this correct?
When using vouchers, guest do not enter a user name and password, just the voucher. Even if these fields are present on the login page, the voucher ID is the one that will be used.
Of course, this ID is the only identification the system has when it shows who's online.
What's the benefit of using Freeradius over a local database? Number of users will be < 100, so scale shouldn't be an issue
Example : "FreeRadius" can instruct the portal for each user a dedicated bandwidth.
Or : How long a user can connect …
Or : .... (see Google "pfSense + FreeRadius) => Answer on first link : https://doc.pfsense.org/index.php/Using_Captive_Portal_with_FreeRADIUS