This box has no released versions. It will not be available from vagrant box add, nor will it show up in search results.

How to use this box with Vagrant:

Vagrant.configure("2") do |config|
  config.vm.box = "g-roliveira/pfsense-ce-2.6.0"
end
vagrant init g-roliveira/pfsense-ce-2.6.0
vagrant up

This box has no active versions.