see wiki.freebsd.org/LXQt for instructions on building from source

Binary unofficial packages has been built for 10-amd64 10-i368 11-i386 and 11-amd64 for lxqt-0.12.0

To upgrade from lxqt 0.11.1 pkg upgrade should do the trick, libfm-qt should be removed and reinstalled manually and lxqt-themes must be installed manually as well YMMV

cd
fetch http://lxqt-freebsd.schmitz.computer/poudriere.cert
pkg bootstrap
mkdir /usr/local/etc/ssl
cp poudriere.cert /usr/local/etc/ssl/
mkdir -p /usr/local/etc/pkg/repos/

create the file

/usr/local/etc/pkg/repos/lxqt.conf
with the following contents
lxqt: {
        url: "pkg+http://freebsd2.freebsd.lan/packages/${ABI}",
        mirror_type: "srv",
        enabled: yes,
        signature_type: "pubkey",
        pubkey: "/usr/local/etc/ssl/certs/poudriere.cert",
        priority: 100
}

   pkg update
   pkg install lxqt
   pkg install lxqt-l10n (optional - translations)
   /usr/local/etc/rc.d/dbus onestart
   add dbus_enable="yes" to /etc/rc.conf

as normal user

   xinit /usr/local/bin/ck-launch-session /usr/local/bin/startlxqt

install optionally gvfs for pcmanfm-qt to work with files over network.