How to enable Ookla script to start automatically after server reboot?

I have installed Ookla speed test on my server. Everything is working but I don't know how to enable Ookla script to start automatically after the server reboot.I am using Ubuntu 20.04. I already checked Ookla website(https://support.ookla.com/hc/en-us/articles/234578588-Linux-Startup-Script-Options) but did understand it properly. They said I need to enable the script on /etc/rc.local I also did not find rc.local on /etc. How can I enable the script to start automatically? I am new on Linux.


Here is my unit file for ookla speedtest service:

# /etc/systemd/system/speedtest.service
[Unit]
After=network.target

[Service]
User=ookla-user
Group=nogroup

WorkingDirectory=/opt/ooklaserver/

Type=simple
KillMode=mixed

ExecStart=/opt/ooklaserver/OoklaServer

TimeoutStartSec=30
TimeoutStopSec=60

Restart=always

[Install]
WantedBy=multi-user.target

Save it into the /etc/systemd/system/speedtest.service file. Then run systemctl daemon-reload and systemctl enable speedtest.service.