Rig Won’t Let Me Animate It - Roblox Animator?

Hi, I’m trying to animate a bus door to open inwards with a bounce animation. I’m trying to rig up the door so I can use the animator editor with it. I’ve gone through countless videos, countless forum tutorials, and when I get to the end and open Animation Editor, it says “Select a Rig to Animate”… even though I’ve already selected the rig.

I’m insure if it’s something I’m doing (probably is), however here is the roblox model file: http://www.filedropper.com/door

I’ve tried searching through tutorials on here, scriptinghelpers and YouTube.

Does anyone have any tips?