I searched for LibreOffice on App Store and I think the only thing under that name was a paid imitation product and not what is meant when LibreOffice is mentioned in this answer.
So I edited the answer with what I think are the right (non-copycat) versions of OpenOffice and LibreOffice.
Since there may be more imitation products, and since I am not a regular user of OpenOffice nor LibreOffice, I would appreciate if someone could double check the edits to ensure they're not inaccurate.
Note: the URLs are the main thing I'm concerned about - just ensuring I actually got the right software (and not imitation software).