We no longer offer to open .fp3 filing is TurboFloorPlan. From V12 the format was changed completely and is not backward compatible.
What you could do is export a DXF file (if V3 will do that) and import it as a trace layer. You can’t then copy the walls etc to quickly re-create the 3D model. If DXF export is not possible, then you can save the plan as a JPG or BMP and use that as a trace layer.