How should I help this person? They refuse to go to therapy/a psychologist

There is nothing really you can do since you don't know this person in real life. But you can keep telling them that they should whenever you encounter them, because they might eventually listen.

They have trauma from therapy, they won’t listen no matter what

And I don’t want to annoy them/drive them away

Good point.

So what should I do?

Like I said, theres nothing really you can do.

pray.

I’m an atheist