80" is a standard height door. 96" is a standard height door. 84" is non standard. A custom woodworker or cabinetry shop should be able to put something together for you.

Go to a lumber yard and ask for a 1 3/4" thick Stave Core Birch Door, it will be a solid lumber core door that this type of lite kit will work perfectly in. I would definitely recommend getting a STAVE core door as opposed to a standard solid core door as the std solid core door will have a particle board core which will not hold up outdoors. As such even a Stave Core door will be veneered and it will be important to keep it properly finished and protected so it does not delaminate.