OBD port not communicating

I assume you meant elm 327?
Some of those you have to look closely at, they may say elm 327 but the cheap knock-offs from China only have the elm 327 software and not the actual elm 327 hardware, and as such they will not work or connect to most modules.
Can you get a simple code reader to connect?
If you want to good elm 327 obdII adapter, wifi or Bluetooth or wired, I bought mine here for about $15.00.
https://www.obdinnovations.com/

I do not have a wiring diagram for the Volkswagen Polo. If the scan tool, etc, is powering up and the check engine light does come on for bulb check, then make sure the wire from the engine control module to the pin at the DLC is okay, so disconnect the plug at the ECM, using an ohmmeter check the wire for an open or short to ground. The rule of thumb is the wire should be under five ohms placing one ohmmeter test lead at the DLC pin and the other ohmmeter test lead at the same color wire at the disconnected ECM plug pin. Do not forget to also check to make sure the wire is not grounded also, so attach one ohmmeter lead to one end of that wire and the other ohmmeter lead to a good metal ground, then the reading should be infinite.
If the scan tool will not power up, make sure the pin from the fuse at the DLC has power when the key is on run/engine off. If the check engine light does not come on for bulb check, make sure the ECM fuses are not blown and check the ECM grounds for being loose.

This is the three cylinder turbo diesel version correct? If yes the OBD II port likely does not actually function as it was not required on light diesels in Europe until 2003. There should be a diagnostic connector under the hood that would allow you to connect to the computer but you need the specific cable and VAG software to actually use it.

European OBD requirements started in 2000 on light gas/petrol vehicles if they had a new engine design. The small diesels and LPG vehicles were exempt until 2003.

There may be a couple modules that can be accessed, like ABS? Or transmission? Maybe the body control module? Hard to say without knowing the full topography of the communication BUS in that vehicle. Especially when it was not required at the time.

Good job!