Hey Davide,
I will try to address the problems you faced as best i can. So first up, the overlap event didn’t fire probably because you don’t have the custom function “OnOverlapBegin” setup as a UFUNCTION() like so
Next thing is you should attach your components to the root right after you create them, that would fix the scaling problem and the box being far from your character.
I can see that you have a root component already so just ignore the SceneComponent lines, and btw the SetHiddenInGame(true) for the TextRenderer should work just fine, it did for me.
Also i recommend using InitBoxExtent instead of the scaling method, but scaling will work as well.
Finally, here is the overlap event and the result
