Can't change the default mannequin walk animation to a Mixamo animation?

Hello, I am somewhat new to Unreal Engine, at least when it comes down to working with animations. I pulled a walk animation from Mixamo and retargeted it to work with the default mannequin and when I drag the Mixamo animation into my scene and press play it works flawlessly. However, what I want to achieve is replacing the default animation with the Mixamo one. When I open up the ThirdPerson_IdleRun blend space and try to replace the walk animation it does not show the Mixamo one. I must be missing something but I cannot figure out what I need to do. Any help is greatly appreciated!

You need to code what Animations you want in the Player Blueprint or Player code.
I don’t now how to do that, but try to google it.