Traccar Server - Unable to start / Unable to login as admin

Hello everyone,
I have installed traccar-linux-arm-5.7 on a raspberry Pi.
It couldn't start at first, with this error:

May 11 17:33:20 hass.wash.lan systemd[1]: Started traccar.
May 11 17:33:20 hass.wash.lan traccar[1185832]: /opt/traccar/jre/bin/java: error while loading shared libraries: libz.so.1: cannot open shared object file: No such file or directory
May 11 17:33:20 hass.wash.lan systemd[1]: traccar.service: Main process exited, code=exited, status=127/n/a
May 11 17:33:20 hass.wash.lan systemd[1]: traccar.service: Failed with result 'exit-code'.
May 11 17:33:30 hass.wash.lan systemd[1]: traccar.service: Scheduled restart job, restart counter is at 1.

I checked the system and libz is actually installed.

apt install zlib1g
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
zlib1g is already the newest version (1:1.2.11.dfsg-2+deb11u2).
0 upgraded, 0 newly installed, 0 to remove and 8 not upgraded.

So I edited the service file and instead of using /opt/traccar/jre/bin/java, I used /usr/bin/java - and this enabled traccar to start:

root@hass:/opt/traccar# systemctl status traccar
● traccar.service - traccar
     Loaded: loaded (/etc/systemd/system/traccar.service; enabled; vendor preset: enabled)
     Active: active (running) since Thu 2023-05-11 18:42:44 EAT; 18min ago
   Main PID: 1231552 (java)
      Tasks: 54 (limit: 8694)
     Memory: 206.9M
     CGroup: /system.slice/traccar.service
             └─1231552 /usr/bin/java -jar tracker-server.jar conf/traccar.xml

May 11 18:42:44 hass.wash.lan systemd[1]: Started traccar.
May 11 18:42:56 hass.wash.lan traccar[1231552]: Database is up to date, no changesets to execute
May 11 18:42:56 hass.wash.lan traccar[1231552]: UPDATE SUMMARY
May 11 18:42:56 hass.wash.lan traccar[1231552]: Run:                          0
May 11 18:42:56 hass.wash.lan traccar[1231552]: Previously run:              42
May 11 18:42:56 hass.wash.lan traccar[1231552]: Filtered out:                 0
May 11 18:42:56 hass.wash.lan traccar[1231552]: -------------------------------
May 11 18:42:56 hass.wash.lan traccar[1231552]: Total change sets:           42

However, I am unable to login with admin/admin.

Looking at the DB, I am not sure which table stores the accounts/users, but the table tc_users is empty.

Is this a consequence of my using the system java instead of the bundled java?

Thank you for any insights.

Using system Java should be fine, as long as it's meets the minimum version.

If you're using the latest version, there is no default user. You have to register one.

Thank you very much. That has worked.
So, does this 1st user become the admin?
It is not quite clear to me just by looking at https://www.traccar.org/quick-start/. Maybe this QuickStart needs a little addition?
Having registered and logged in, I have disabled registration on the server, which I believe makes my account the only one, unless I create others now.

This has changed recently, so probably we haven't updated some documentation. The first user becomes the admin.