I am not an expert in this field, but I assume you have a title right now called "Aufenthaltsgestattung"? I googled a bit and saw that the "Bundesagentur für Arbeit" (German Employment Agency) generally has to allow you to work if you are in that status. They should also be able to tell you, if working as a freelancer is fine as well. I also googled about that and saw that there are freelancer online-plattforms encouraging refugees to work on their plattforms, so it seems working as a freelancer should not be a problem once "Bundesagentur für Arbeit" allowed you to work in general.
As for the TAX number, I am pretty sure you need to apply for that at your local "Finanzamt" (Tax Authority). Normally you just fill out a form and hand it in and that shouldnt take that long.
Hope at least I could help a bit, even tough I am no expert in this. But I will be glad to look for further details, if you need any help!