Where do I find the link to download?
Look on the download page; under the version it says something like:
Help for offline use: English (GB) (Torrent, Info)
Just click on the link to download an installer package. Note the offline help opens in your browser
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to the left and, karma permitting, upvote it. If this resolves your problem, close the question, that will help other people with the same question..
Some confusion might appear due to OP searches for 6.1.6.3, while download pages only offers 6.1.6 (at least I’ve been a bit confused, when using LibreOffice for the first time). This comment is just to assure OP that, if he clicks to download 6.1.6 helppack - finally 6.1.6.3 will be installed version.