Translated into tech:

They mean professional programmers, those who write code for a living and have at least one formal git repository.

That is meaningless from a legal standpoint. Press credentials are not a real thing with any official weight. And if someone reports news as a volunteer for a non-profit organization are they not a journalist?

They are a real thing and bring significant privileges in some jurisdictions. In some of them, press credential is actually government issued and yes, they tend to exclude volunteer journalists. It does not mean volunteer journalism is illegal, rather that volunteer journalists do not confer the same privilege as a professional one.

I am so thankful to live in the USA where anyone can be a journalist and no government credentials are needed.