If you live in the Netherlands and also have a valid BSN, you can register with it on 777.nl. You can go through the initial registration steps and upload your ID. Then you can also verify your address via your bank (IDIN).
After that, you can send a document showing your BSN to our customer service via support@777.nl . This could be a photo of your health insurance card or, for example, a letter from your municipality or the tax authorities. It is important that your name and the full BSN are visible on it.