Welcome to the Wefugees Community and thank you for your question.
To marry as a foreigner in Germany is indeed not easy as the registry office (Standesamt) is asking for various documents. You may want to check our blog on this topic for further information including a list of the potential required papers.
In case you don't hold a certified copy of your passport (which the registry office may accept), you could ask the BAMF to issue one for you. It is possible that the registry office is also asking for a legalization of your passport which may has to be done by the German embassy in your country of origin. I am unfortunately not an expert on this topic though and I know that procedues may vary from country to country as well. It is the best to consult the registry office directly to get reliable information on your individual conditions.
As it is sometimes not easy to get in contact with the authorities (especially to receive a reply), you could also ask a refugee counselling office for support. Just let us know if you need help in finding an organization close-by.
I will also link my colleague dear @mbeon-fardeen here. Maybe he can correct me or give some additional information.
In any case, please also don't hesitate to get back to us with any further questions.
All the best,