Install Mount to Case
Carefully insert the mounting plate into the case with the ports facing the outside. Line up the two tabs on the side of the plate with the standoffs on the case. The mounting holes should be lined up as well.
While holding the mounting plate in place, insert longer M2.5 x 10mm sized screws into the holes on the outside of the case. Drive the screws until they protrude through the tabs on the mounting plate.
Secure Mounting Plate
To properly secure the mounting plate to the case, we'll need to install 2x M2.5 washers. This can be a little tricky to get your fingers into the case at this point, so I suggest using tweezers to place the washer on to the screw threads. Fasten the screws until fully tightened.