Okay, yeah there was a bit of a misunderstanding! Typically the question people ask with widgets is about the timeline NODE on the event graph, which is unavailable in UI blueprints.
So you’ll right click and add two keyframes. One for the beginning, and one for the end point. Then on that keyframe, you need to go down the list on your window there beneath offsets -of which you’ll likely just change the Y value- and input the spot you want it to move to. Now if this is going to be for each option, you’re going to have to have a separate animation for each one, I believe. Alternatively, I think you can use “On Mouse Hover” on each button, and set the values for the keyframes of the animation on the fly, then have the spider image play that animation with it’s current location as start and the spot next to the button as end. Let me test some things, UMG is so different from standard blueprint. I’ll be back momentarily! 
Edit: Okay I had an issue and am currently reinstalling UE5.1. Just to be clear… You need this to slide up and down, just instantly moving the spider to a spot next to the button would be unacceptable? Because it would be WAY easier and I could tell you how to do that without having to wait on the installation.