I finally compiled LibreOffice online and reached my first milestone. Once this was done I had to create a new subdirectory on my machine:
sudo mkdir -p /usr/local/var/cache/loolwsd
Because I had to run the LibreOffice online with the rights of the user I had to change the ownership of that directory:
sudo chown `whoami` /usr/local/var/cache/loolwsd
Then I could start the online office with:
Once the server of the online office is up I get the information in my shell about the URL of the office with the direct link to the usual hello world document and of the admin Console. The latter one is https://admin:admin@localhost:9980/loleaflet/dist/admin/admin.html
The first one depends on the special configuration and file structure of your machine. It starts with:
I pointed my browser to this URL and get to the hello world document. But first I had to deal with the security configuration of my browser (Firefox), which complains about an unknown certificate.
And I could also get to the admin console with the URL that was displayed to me in the shell.