These are the steps I followed so far on my Ubuntu machine:

1. Install LibreOffice sdk: sudo apt-get install libreoffice-dev

2. Locate the setenv file for LibreOffice by typing the following command on the terminal: locate setsdkenv_unix.sh

3. Try executing the script: . /usr/lib/libreoffice/sdk/setsdkenv_unix.sh

4. Install Microsoft SDK for Unubtu/Debian/RHEL: sudo apt-get update && sudo apt-get install -y dotnet-sdk-8.0

5. I believe the development environment is set up for C#.

6. If you can post your sample code, I will try to compile and execute it.