If you want no shadow on the background, you can either

• Separate the subject farer away, so that the shadow falls outside of the frame, or
• Slightly overcook the background to force it white despite shadows

If you want no shadow on the floor:

• Stand the subject on a white acryllic sheet.
• Raise it a bit above ground level, so that the camera can’t see where the background meets the floor. Place the camera far away and low to help with that.
• Light the subject normally. Don’t bother with lighting the floor panel. It’s reflective and will mirror the background into the camera.

Assuming you have even white on the background, you will also get even white on the “floor”. No need to overexpose anything. You can model the white sneakers properly, despite them being embedded in background white.

With still subjects, this setup even supports foreground/background exposures for automatic clip paths, because the two light groups are pretty much independent.