You cannot do what you are trying to do:
Launch Character is a function that works with Character types. Your Slimemove Blueprint, is of type ‘Actor’. Actor DOES NOT have LaunchCharacter available.
I think what you are trying to do there, is say: if my character hits a Slimemove, damage the Slimemove and launch MY character, right? In that case you DO NOT NEED to connect to Launch Character, out of your cast! You are trying to launch the Slimemove when you do that! Why? Which brings us to the other potential problem here: You have this node logic inside your Slimemove actor… why? Can Slimemoves (jump on and) attack other Slimemoves? Seems to me this logic belongs to your Character’s Blueprint instead. There you can just right click and use a Launch Character node (and again, you don’t need to connect anything to its Target pin, if it’s your own character that needs to be launched). But there you need to cast to Slimemove to detect that you have hit that enemy.
You can also do this here (but it seems the reverse way to me), but instead of CastToSlimeMove, just cast to your character actor blueprint/type instead. That way the connection to LaunchCharacter will work fine.
I hope I’m making sense. If I have not understood what you are trying to do, please clarify further.