firewall-cmd on OpenVZ CentOS 7

So I've been trying to set up a webserver on my VPS with CentOS 7.
To do this I've used this tutorial. Installation of MySQL/MariaDB and PHP worked successfully. However I can't access my server, because I haven't allowed external access yet.

To do this I am forced to use these three commands (according to the tutorial):

firewall-cmd --permanent --zone=public --add-service=http

firewall-cmd --permanent --zone=public --add-service=https

firewall-cmd --reload

The command firewall-cmd wasn't found because according to this thread, OpenVZ installs a stripped down version of CentOS7, so I used the commands from there.

However, following error message popped up when using systemctl start firewalld:

Job for firewalld.service failed. See 'systemctl status
firewalld.service' and 'journalctl -xn' for details.

systemctl status firewalld.service -l shows this info:

firewalld.service - firewalld - dynamic firewall daemon Loaded:
loaded (/usr/lib/systemd/system/firewalld.service; enabled) Active:
failed (Result: exit-code) since Mon 2016-07-18 04:31:46 EDT; 6min ago
Process: 12522 ExecStart=/usr/sbin/firewalld --nofork --nopid
$FIREWALLD_ARGS (code=exited, status=1/FAILURE) Main PID: 12522
(code=exited, status=1/FAILURE)

Jul 18 04:31:46 Christof2 systemd[1]: firewalld.service: main process
exited, code=exited, status=1/FAILURE Jul 18 04:31:46 Christof2

systemd[1]: Failed to start firewalld - dynamic firewall daemon. Jul
18 04:31:46 Christof2 systemd[1]: Unit firewalld.service entered
failed state.

FYI: I did everything from a fresh installation of CentOS7, if you want I can simply reinstall CentOS and do one step differently, if that helps.