Problem with new light phone:(

So I just opened my new Lightphone, inserted a SIM card, and there's nothing in the Lightphone.

So I went to the Dashboard to ade tools, clicked "Phone", and all I see is my phone number, and "help, my Lightphone is not listed".

What does it mean, and why is it so difficult? What should I do now? This is really discouraging.

Im in Poland, my carrier is T-Mobile.

Does anyone has any idea/had this issue?