Anyone know how to attach the corner wedge to the backplate for Wire-Free Doorbell?

and which backplate to use? We are doing the wire-free option, so you would think it is just the Back Plate (E in the directions) but that doesn't seem to work so we have also tried the Screw Back Plate (D in the directions) but that isn't working right either. And Roku refuses to make directions for how to do this. There are no directions in the box nor online. And if you contact customer service, they have no idea how to do it either and will just repeatedly say "I'm sorry to hear that" when you ask them a question, instead of answering the question. I am literally already fed up with Roku and the awful directions and awful customer service. Hoping someone on here can explain how to attach the corner wedge to the backplate? Any way we have tried it, it doesn't attach well and looks awful/wonky. It just doesn't attach well and it is requiring way too much force. And we aren't even doing the wired option, we are doing wire-free so we don't have to worry about all the wires going through the holes, but this still isn't making sense (BECAUSE WE DON'T HAVE ANY DIRECTIONS!!!). Sorry, I am very frustrated right now if you couldn't tell. I have never dealt with such a difficult company before. 

Also, to any Roku officials who read this: get your dang **bleep** together and post some directions to this already. It is ridiculous that directions to this don't even exist yet. It's embarrassing that you guys don't have this figured out yet.