The base plate protects your substrate from contamination and facilitates the removal of the finished compost due to the smooth surface.
If you place the composter on paved surfaces such as terraces or concrete, the base plate is certainly recommended. If the composter is placed in the garden, you can SUPERCOMP on bricks or do without a paved base. This is also not a problem. However, make sure that the composter is set up horizontally (level the area before installation).