I get an error:
“LibreOffice” is damaged and can’t be opened. You should move it to the Trash.
I checked the MD5 on the .dmg file and it seemed fine.
Oops, I did some more thorough Googling and found the answer. I needed to “Allow Apps downloaded from Anywhere” in my security and privacy settings (yikes).
After opening for the first time, I could change the security setting back to something more conservative.
Source: https://listarchives.libreoffice.org/global/users/msg46767.html