If you have a data subscription for the Sunrise card, which of course costs money, the SIM card should already be active. Without a subscription for the card, of course, nothing works. Once the SIM card is active, insert it into your mobile phone and block the PIN query in the SIM settings. NO MORE PIN REQUEST!!! You can't enter a pin code on the B525 router anyway.
The SIM card is now pin-free - you can insert it from the mobile phone into the B525 router and it works - provided your subscription allows it. 4G data traffic is chargeable.