Your employer may need to apply for a provisional Residence Permit (MVV) for you. The employer submits an application both for an mvv and a residence permit at the same time.
The IND (Immigration services) assesses the application and notifies your employer/host of the outcome. When it has been granted, the Dutch embassy/consulate will be notified as well.
From that moment on you can collect your MVV from the Dutch embassy.To collect your MVV at the Dutch embassy or consulate you will often need to make an appointment.
Also interesting for you: embassies, before arrival.