Having a valid travel document (passport or identity card) shows that you are lawfully staying in the Netherlands. The travel document has to be issued by an EU/EEA country or Switzerland.
You do not need a work permit to work in the Netherlands, except if you have Croatian nationality. As a Croatian citizen, you may only work if your employer has a work permit for you.
You may not be a risk to public order.
If you are planning to stay in the Netherlands for more than 4 months, you have to register with the Municipal Personal Records Database (BRP) of the municipality.