Because you are not allowed to work before or after the birth, you receive no salary from your employer. Instead, you receive maternity pay from your health insurer. This means that you must submit an application to your insurer in a timely fashion.
For questions regarding maternity pay, it is best to speak to a counselling agency for pregnant women or a family counselling agency. You can get addresses from an MBE (Migrationsberatung [Immigration counselling]) office or via chat.