In the Netherlands, you cannot become the legal owner of a property without a notary. Signing the purchase agreement does not transfer ownership.
The notary prepares the deed of transfer (leveringsakte), which is signed by both buyer and seller. This deed is then registered with the Dutch Land Registry (Kadaster). Only after registration are you legally recognised as the owner.
The notary is an independent legal professional who ensures the transaction meets all legal requirements. They do not act as your personal advisor.