I haven’t read the tutorial, but:
1 - When using ‘Construct <Item>’ (in your case Itemobject), you will see some basic pins + any exposes pins. The base ones are the ‘Class’ and ‘Outer’.
2 - ‘Text’ and ‘Instigator’ are coming from your class. ‘Instigator’ is specifically coming from an actor (base clasas)
Instigator specifically, is: “Pawn responsible for damage and other gameplay events caused by this actor.”.
Many times you won’t actually need it (unless you use it on your own), although it’s good behavior to provide it anyway - if it’s relevant.
3 - You should probably consider deriving your class from UObject rather than AActor.