Make a docker-compose.yml
Describe your server and download the file. It is written in this browser tab: nothing you type here is sent anywhere, passwords included.
Mail and HTTPS (optional)
Without mail, the first account you create is the owner and an admin adds others under Settings, Users. Mail sends only account confirmation and password reset.
Without TLS in front of the app this locks you out.
The name or address people reach this server at, with no https://. Links in mail point here.
Leave it empty for a relay that needs no sign-in.
docker-compose.yml
Save it in the folder it names, run docker compose up -d there and open the address in its first lines. The first account you create is the owner. The install guide explains every setting.