The bureaucracy in the Netherlands is highly digitized and efficient, but strict. Here is exactly how the systems work.
Golden Rule: Keep all physical letters from the government. The Dutch government communicates critical information (like activation codes and tax assessments) primarily via traditional mail in blue envelopes.
You literally cannot live legally without it. It's required for working, opening a bank account, visiting a doctor, and paying taxes.
Make an appointment with the local municipality (gemeente) where you'll be living. If you don't have an address yet, you might be able to register as a non-resident (RNI) to get a BSN temporarily.