How can I get/play animations from the catalog?

I'm making a simple game, that makes duplicates of players which you can control like units.

I'm trying to utilize HumanoidDescriptions to provide the player information.
Now, I've already figured out that the asset ID provided isn't actually for the animation, it's for the full asset, meaning I need to use insert service to obtain the Animation for my little unit.

Only one problem. The animation, when inserted by ROBLOX, is just a KeyframeSequence.

How.. exactly do I make this play?
Isn't this the type of thing that needs to be uploaded first?