Help with DDNS settings for Njalla

Hi, I’m trying to learn about setting up DDNS using my Surf SOHO router instead of DDCLIENT on linux. I’m planning on purchasing a domain from Njalla, but I have not yet done so because I want to make sure that I’m able to setup DDNS before I do so. I’ve looked at the Njalla documentation and the Surf SOHO documentation, but I’m uncertain and was wondering if anyone could help me. I’ve selected “Others” for DDNS providers, and the way I’m guessing I need to do this right now is input the following for URL:

https://njal.la/update/?h=<subdomain>&k=<key>&auto

Then my userid and password? What if my account has 2fa? I’m confused at what I need to include for hosts. Thanks for your help!