Most of our floormats are shipped in either a box or a giant polybag. In either case, the mats might be folded, or will have been jostled around during shipping. As you unpack them and place them in your Tesla, give them a few days to re-find their natural shape. Warming up the car will accelerate the process. If you don't plan to install them right away, please unpack them, so they can be allowed to relax and regain their natural shape.
The backing layer is like a giant sheet of hooky Velcro. This means they're never going to slide around. It also means when installing you should pay attention to lining up the edges and corners, as they'll try to grab hold of the carpet as you're placing them. For the trunk mat, it's probably easier to drop the seats, and place it into position. For the front mats, just be sure to make sure they're nicely tucked into the corners.
Finally, if you ever need to clean them, dry dirt can just be vacuumed, but if things are a bit messier, just take them out of your car and hose them down. 95% of the water will just run off, then just give them a shake and leave them outside to finish drying.