Welcome to the Wefugees Community and thank you for reaching out to us.
I think it is in general a very good idea to look for an Ausbildung and to get qualified for the German labour market. The first step needs to be to get rid of the "Arbeitsverbot", the prohibition to work. This will get very difficult if you are from a so-called "safe country of origin" (sicheres Herkunftsland/§29a AsylG). At the end there are a few possible reasons why you might not be allowed to work with your Duldung. One of them is, that you are still obliged to stay in a reception centre (Erstaufnahmeeinrichtung). Another one might be, as @MB mentioned, that the immigration office is accusing you not to contribute in clearing your identity.
However, as many factors need to be considered, I would highly recommend you to get some legal counselling from a lawyer or a good migration counselling office. Together you can check whether the work prohibition is lawful and individually discuss your options.
Am I right on this dear @mbeon-Christine or @mbeon-Rukundo and is there anything you would like to add?
In any case, don't hesitate to contact us if you need support in finding a respective office in Potsdam or if you have any further questions.
All the best,