Super simple.
The STL exporter does not come enabled out of the box. It is part of the program though. Just not enabled.
Go to edit, preferences, add-ons, check the box for the STL importer-exporter. Done.
I say that kind of flippantly because the 3d model kind of needs to also match your cnc carving modeling needs.
But way easier than 3d printer modeling needs. lol