I Just open the *.fcstd file. Then switch to the draft workbench. Then i select to to surface (also works on the bottom surface). Then i clicked on Shape2DView see https://wiki.freecadweb.org/Draft_Shape2DView . Then i mark the result (Shape2DView) and go to File --> Export. The you should choose as file type *.dxf , give the file a name and click Save. Final filesize < 50 kByte. More easier is not possible, this is FreeCAD (or any CAD) rock bottom.
The file you attached now is also 3D, which is for a lasercutter invalid.
Greetings
user1234