This page lists the supported Masso G-codes: Supported G-codes
Based on this page, the linuxcnc post processor should work but you should deactivate tool length offset ( option --no-tlo ) as the Masso list does not include any offset G-Codes “G43” etc. (this part taken from FreeCad Forums)
To set this as the default machine then:
“Edit” → “Preferences” → “Path” (in the ribbon on the left) → “Job Preferences” → “Post Processor”
Well this is what I am going to try when my machine shows up in 5 weeks