Captive portals are not an exact science on any BSD and even on many Linux distros.
Here are my tricks for every day use:
1) set Firefox as your default browser.
2) don´t start local-unbound as you need their DNS for redirection. If you really need local-unbound, comment out the related lines in resolvconf.conf and add ¨prepend domain-name-servers 127.0.0.1;¨ or ¨append domain-name-servers 127.0.0.1;¨ in your /etc/dhclient.conf. As a matter of fact, I am using unbound and dhclient from ports.
In case of a new install, you have the following options:
3) connect your smartphone to the captive portal and use it as a hotspot, or
4) boot a live USB stick of a GNOME-based linux distro such as ANTERGOS (they have a thing called
CAPNET-ASSIST that seems to work very well), login and reboot with your FreeBSD install. It works for me at Starbucks.
In any case, don´t waste too much of your time as this is not an exact science.