2006 Prius Putting Back Casing After Blower Motor

I just replaced the blower motor in my 2006 Prius, getting in there was pretty easy, but I cannot get the white casing underneath back in place to save my life. I can get the front screws right behind the glovebox lined up, but not the back, so I can’t get the transmission control back in place either, since the back of the casing is too low and blocking where it needs to screw in. I think it might be an issue getting the little arm to the left to fully slide into the hole in needs to go in - it keeps getting stuck at a funky angle.

Any tips or tricks? Or is this an I just need to mess with it until I get it situation? Many thanks