Different size in slicing software

i use the free version and design in stl
when I open the design in the slicer it says the object is too big and should it autoscale? If I don’t do this will I get a mega design outside the PCB? If I make a design that is 5cm high, 3cm deep and 5 wide, my slicer software says this while the print area is 20x20x20cm??

both in the slicer of XYZ and in Ideamaker

Is it because i don’t pay for the app?

Please help.

Prior to exporting your STL file, did you set the units to millimeters?


Thanxx Thats the solution many thanks