Weird skewed shapes

Hey so im very new to the laser world. I have this cheap laser called sculpfun S30.
Problem is i can’t get it to work properly. When i want it to cut me a4 sized box 210x297mm it gives me some skewed shape that is not A4 sized.
Did anyone meet this problem? What can i do?

Inside of the cut out box i placed A4 size paper

Go through this guide to make sure your frame / mechanics are set up correctly: Guide to mechanical adjustments and maintenance
The frame isn’t (and can’t be) set up perfectly from the factory. You need to fine tune all components carefully.