I just joined Ask Ubuntu and wanted to answer one question at https://askubuntu.com/unanswered but there is no answer field to enter my answer. Why?

I have 1 reputation and I tried to contribute to raise it so I can unlock some activities but I don't understand why I can't do that. One example from today is https://askubuntu.com/q/1272864/944289 (an unanswered question where I cannot see any answering field to write into).