Matt ,
judging by the measurements that you have just posted , your door is 2.8 x 6.9 , that is to say 2800 mm (2 M 800mm) X 6900 (6 M 900mm) about 3-4 times larger that the bench plans call for . :rolleyes:
In fact that is a Huge door. :o
You had better measure that again :U
Note that it is customary , in this part of the world to give the largest measure first.
PS. don't give imperial measure in metric form , it is also confusing ,even when it is notated