Check which version of LibreOffice is compatible with your version of PhixFlow: System Requirements and Compatibility.
Windows
Download the the latest patch of a compatible version of LibreOffice from: https://www.libreoffice.org/download/download/
Install on the PhixFlow server using the default settings
Complete configuration of the PhixFlow integration with LibreOffice: Configuring PDF Conversion
Linux
Run the following commands to install LibreOffice from the repository (this adds the LibreOffice PPA, this is required to obtain the most recent version of LibreOffice):
sudo add-apt-repository ppa:libreoffice/ppa sudo apt update sudo apt install libreoffice
Make sure that the Tomcat installation directory has the correct ownership, e.g.:
sudo chown -R tomcat:tomcat /opt/tomcat