DIAGNOSIS A leak from the bottom casing usually means an internal hose connection has come loose, the drain plug isn't seated correctly, or the water tank has a crack.
FIX First, check the silicone drain plug on the back or bottom of the unit. Make sure it's pushed in all the way and twisted to lock if it has that feature. If that's secure, the leak is likely internal. You'll need to unplug, empty, and tilt the machine over a towel to see if you can spot a disconnected tube near the pump or a crack in the plastic reservoir.
IF THAT DIDN'T WORK If you can't see an obvious issue, the leak might be from the internal condensate pan or a seal on the evaporator assembly. That's not a user-serviceable fix and means contacting support.
HEADS UP Always move the unit to a sink or towel area before removing the drain plug for cleaning. It will, by design, release a lot of water quickly.