Show progress in walk challenge

I joined a walking challenge for 2022 phase 1 but after 2 hrs walk nothing has happened.

I read somewhere that you need to log it (gps is apparsntly not enough) but AS walking. However in my app I can only do this manually. Which doesnt register in the challenge.

And on my watch (forerunner 225) only running, biking and "other" are my options. 

What should I do?

Thank you in advance

Elias