Open DXF in Illustrator
If there are double lines it might be caused by infill and contour lines overlapping. Ask the maker of the DXF file to give the infill a different color than the outline.
In illustrator, select an infill or outline object
Select > Same > Fill & Stroke
Delete
Check for errors in outline mode (cmd+Y)
Select a shape
Put it in a new document (copy, make a new document, paste)
File > Export > Export As > Format: DXF
In Fusion 360: Insert > Insert DXF
Select the shape, extrude
CMD + click the object in the tree > Save As Mesh > OBJ
Import the OBJ file into Cura and check the dimensions. Now it's ready to print