I went through the tutorial to have a look at it. From what I see you have everything modeled correctly if you want the corners to match up go back to the very first base flange that you created and edit the feature, then make sure that the material is to the outside of the sketch lines that you have sketched. They do not say to make the part like this in the tutorial but if you set the material to the inside then your last flange will be too long.
If the material is to the inside the finished part will look like you have modeled it.
In a real work situation you would be better using the up to vertex command for the last last edge flange with the parallel to base option, this will mean that the edge flange will always be the same height as the vertical side so if you make any changes to the height of the vertical side you would not need to try and make adjustments to the edge flange separately.
As this is only a basic guide as to what you can do in SW with sheet metal parts it does not really matter if you have the material to the inside or outside of your initial sketch and it does not matter is the edge flange is too long so long as you understand how to use the sheet metal features in SW.
Hope this helps