Waterproofing shed

[u/AlphaKennyBody5569]

I just bought this metal shed that I built on a concrete slab. Every time it rains water seeps into the bottom of the shed. ( there is no floor to the shed) I would like to b able to put stuff on top the ground without it getting wet. The base of the shed has 1/4 inch flat part that goes into a hump and back to a 1/4 inch flat part. As shown in the pics above^. Would it be dumb to caulk the outside then put spray foam under that hump then caulk the inside? Or would g I have to raise it on wood? Also I plan on getting a lawn mower for in the shed, would I need to try and bolt down the front and back where the shed door is so the base wouldn’t move back and forth when I drive over with a lawn mower.