Welcome back to the Wefugees Community and thank you for reaching out to us.
Very similar questions were raised on this platform before. You may want to check threads like I'm a failed asylum seeker in Germany - How can I marry my US girlfriend? or Can I marry my German girlfriend without a passport? for more information.
For an overview on how to marry in Germany and a list of required documents please see our blog.
In general, you can marry as a Duldung holder in Germany. However, the registry office (Standesamt) will most probably ask for your passport as one of the required documents. I would recommend you to get in contact with the Standesamt directly and explain which documents you can provide and why you are not able to get a national passport. The final decision will be with the individual civil servant. I am afraid that I can not give you a better or more promising answer on this.
Nevertheless, please don't hesitate to get back to us with any further questions.
All the best,