As a rule, if you work and pay income tax in the Netherlands, you are subject to the Dutch Social Security Legislation. Therefore, you have the legal obligation to hold a Dutch Health Insurance Policy.The same applies if you live (reside) in the Netherlands and don’t have a job, though the definition of what constitutes ‘residence’ is less clear. The mere fact that you are registered at an address in the Netherlands or have a Residence Permit does not necessarily mean that you are a resident in terms of Dutch Social Security and therefore have the obligation to hold Basic Health Insurance. Check if an exception applies to you.
Also check this official site for more information: Health insurance | Government.nl
If you are required to hold a Basic Health Insurance basic health insurance, you are free to choose a provider.
If you quit your job but remain living in the Netherlands, your obligation (and right) to hold a Basic Health Insurance may change. Check which situation applies to you in that case and, if needed, arrange another form of Health Insurance.
If you fail to get Dutch Basic Health Insurance while having the obligation to do so, you will likely receive a letter from the CAK (a governmental organization) and may be fined. Check here what to do.