I cannot say if you missed something.

Did you watch the video?
Did you clean the bottom flange of the tub where the sump fits into?
Did you check that area to be sure it does not have a crack/hole etc.?
Sometimes a light coating of lithium grease is helpful. It helps by preventing the ribs from grabbing and twisting and then not sealing.
Is the motor sitting nice and level. If not it may be pulling it's connection point on the sump down so it cannot seal correctly. Take sure the throat of the motor/pump housing is up and tight also that the rear motor support wire is installed.

If you do get it to seal I would leave the kick plate off for at least a week so you can be sure that there is not leakage. This is not a good idea if you have small children or pets that can get under the unit.

It is a good idea to put a drip pan under dishwashers. Something like the plastic trays they use for boots etc. will do. They have a lip all the way around but it is usually low enough that the tray will fit under your unit and cover most of where the water may leak.
You then cut out part of the lip on the kick plate side. Now it you have a leak it will drain out onto the floor in front of the dishwasher so you know there is a problem. Beats finding out that your floor has rotted out if there is a slow leak from the unit.

I also make a small tray out of tin foil for under the water valve as this is usually outside the main unit tray.