Wow! It does look like I wrote it such that it won’t require an API key if it’s a public topic.
Or maybe not?
I pushed a fix, so you can do a git pull and it should work now with an empty apikeys file. (I think you need to create an empty one, though). It will download a topic to a text file.
I wrote it for off-line analysis of discussions, however, so I’m not sure how useful it’ll be without some work. I think that it should let you download the stuff locally, but won’t be much help (as it is) to move it to another Discourse.
If you want it moved to another Discourse and it’s a public topic, you’ll need to, say, get this tool to something different. If you have a budget you can contact me or post in Marketplace.