You need a stereo audio amplifier between the Pi’s analogue audio out and your speakers.
If you’re ok soldering something like the following should work and could be powered from the Pi’s 5V.
As you have discovered the version in the repository is hopelessly outdated (and will NEVER be fixed, because of some Debian politics).
You can safely purge the installation without losing any of your files.
Just download the Linux ARM 32bits version from https://www.arduino.cc/en/Main/Software
See https://arduino.stackexchange.com/a/44813/3879 for ...
what kind if "server" is this?
my best guess is that the two USB ethernet adapters connected to the server are giving ip addresses on the server, not giving IP addresses to the pis. since there are 169.254 addresses, you don't have a dhcp server, so your server is giving itself an apipa address. and there are probably good reasons for a machine to not give ...