Cannot enable user service. "Failed to get D-Bus connection: Connection refused"

I created a duniter service.

admin@Xroklaus:~ $ cat /etc/systemd/user/duniter.service 
[Unit]
Description=Duniter node
After=network.target
ConditionPathExists=/home/folatt/.config/duniter/duniter_default/duniter.db

[Service]
Group=folatt
User=folatt
Type=forking
ExecStart=/usr/bin/duniter webstart
ExecReload=/usr/bin/duniter webrestart
ExecStop=/usr/bin/duniter stop
Restart=on-failure

[Install]
WantedBy=multi-user.target

After rebooting, it does not show up however:

admin@Xroklaus:~ $ ps -ef | grep duniter
admin     3438  3418  0 19:38 pts/0    00:00:00 grep --color=auto duniter

And I can’t see why.

folatt@Xroklaus:~ $ systemctl --user status duniter
Failed to get D-Bus connection: Connection refused

Did you enable (= make it start on boot) with systemctl enable <yourservice> ?

I tried.

folatt@Xroklaus:~ $ systemctl --user enable duniter.service
Failed to get D-Bus connection: Connection refused

[update]

For some reason package libpam-systemd was removed on both of my Yunohost servers.

admin@Xroklaus:~ $ sudo apt-get install libpam-systemd

On to the next issue…