Welcome back to the Wefugees Community and thank you for your question.
For the so-called "Chancen-Aufenthaltsrecht", people are issued a residence permit according to section 104c of the German Residence Act (it is a new section) for a period of 18 months (not only 12 months, as the former draft of the law described). While having the residence permit according to section 104c, people need to fulfill the requirements for either section 25a or 25b of the German Residence Act and switch accordingly.
Please note that in the future applicants will be able to apply for the 25a until the age of 27 years.
I hope this helps and don't hesitate to get back to us with any further questions.
All the best,