During the registration for the electronic signature, you get identified in an online or face-2-face identification process and register your future signature approval at the same time. Sometimes, you need your signature approval, which means pre-installed and activated, e.g., Mobile ID. Other signature approval means you do not necessarily require an installation before the identification. e.g., password and SMS code method (PWD/OTP).
The registration and linkage to your identification often happen when accepting the terms and conditions of the Signing Service because, in this step, you confirm and consent for acceptance with your signature approval means. You can compare it to a first electronic signing request.
Afterward, you use the registered signature approval means for each electronic signing request.
Just so you know, if you change your signature approval means, you usually have to re-identify and re-register for the electronic signature.