I realize the documentation on the Export part is not great, but in brief:
You can run the text exporter by selecting files and then going to File > Export... and choosing "Text Exporter" from the dropdown.
(To do this for an entire catalog, you can just put "" in the search bar to get a Contact Sheet with your entire catalog, and then use cmd/ctrl-a to select all)
If your goal is to create a spreadsheet, use {tab} in between {variables} to pick what you want to export from the files that you selected.
In my test I used:
{filename}{tab}{folderpath}{tab}{keywords}
I named the exported file with .tsv as the extension and then opened that in Excel.
One caveat: the text exporter wasn't originally written with millions of files in mind, so I am not sure how it will perform on very large catalogs. The test I just did with 8500 images went fine. It may take some time to chug through larger numbers of files. I am curious to know how this will do with larger catalogs, and when I rebuild my catalog I will try it.
Mick