I am running Sierra because that’s what comes with the updated computers.
Please add the complete filename (including extension) and file size, so that we can figure out what went wrong.
If it was me I’d try downloading via a “Torrent”. Just click on the “Torrent” link on the download page. Torrents have the advantage of having an automatic integrity check for the file built in.
Good luck using it if you do download it. Right now the Mac version is so slow it is virtually worthless, unfortunately. Until it gets fixed to work reasonably well on a Mac, I’d suggest NeoOffice, which works perfectly.
I had a similar issue with a new iMacOS
Check if the “System Preferences”“Security and Privacy” “General” allow down loads from…isn’t defaulted to only Mac or App Store, change it to any down load LibreOffice and then reset back to default if you want
If your internet connection is slow it may also be worth stopping the “Energy Centre” switching off mid download by changing the default time on to “never switch off” until down loaded and then reset the default afterwards to what suits.
Good luck