Running as a service in FreeBSD

Probably it is a quite dumb question, but someone could give me the directions to run zigbee2mqtt as a service on freeBSD?

I installed it in a jail because I have a NAS with Freenas OS, and all is running without problems, but zigbee2mqtt stops workings as soon I close the shell. As I use Freenas mostly by the GUI and rarely deal with command line, I can’t accomplish the instructions of the “Running zigbee2mqtt”, topic 5 "5. (Optional) Running as a daemon with systemctl ", as it was written for Linux.

After some research I’m guessing that the script needs to be at “/usr/local/etc/rc.d” but trying to run it with “service zigbee2mqtt start” gives me “[Unit] not found” “[Service] not found” etc.
Probably it’s very simple for those who know how to write a script in FreeBSD.

Thank you