Collabora Online is Collabora's branded version of LibreOffice Online. They also have a version they call Collabora Online Development Edition that you can find here for personal use: https://www.collaboraoffice.com/code/.

There is no stable edition of LibreOffice Online but you can find a daily build of the master branch for Docker at https://hub.docker.com/r/libreoffice/online.

Both LibreOffice Online from Docker Hub and Collabora Online Development Edition have a configured limiation of 20 connections for 10 different doucments so personally, I'd recommend building from source. You can find the source code for LibreOffice Online here: https://git.libreoffice.org/online.

I suspect the lack of a stable version of LibreOffice Online is intentional as a way to try to drive more business towards companies such as Collabora.