thank you for sharing your question with the wefugees community.
The residence status is not important regarding the process of marriage. You can get married with a Duldung. You'll need the necessary documents (e.g. Passport, Birth certificate...) You can inquire about the necessary documents at Standesamt (Registrars' office). You can get more information regarding marriage on the wefugees-blog: https://wefugees.wordpress.com/2018/04/20/heiraten-in-deutschland-how-to-marry/
I hope my answers were helpful and I would be very happy if you would contact me again with further questions. I'm a consultant with mbeon and I‘ll be glad to help you over a longer period of time. Mbeon is an online advice for migrants via the mbeon app, which you can install on your smartphone for free. Download it from App Store or Google Play Store. You can find me in the mbeon app and get confidential individual advice in a secure virtual space without other people reading our conversation. Further information: www.mbeon.de.