Question about AVM FTTH Router FRITZ!Box 5530, with AON SFP

I ordered the FritzBox 5530 with XGS-PON from CitySun.ch. It's expensive. After installation, a Swisscom page appears on which you have to enter the OTO number (on the fibre connection socket), the socket number (usually no. 2 for third-party providers) and the NSN number (you can obtain this from Wingo on request).