You’ll have to refer to the original tutorial for how to set that up - as I mentioned before I just got rid of having two separate classes for each item (that’s what those screenshots earlier in the thread show how to do), and just store the UsableActor itself.
As for why it’s not working on dedicated, try to find why the Add Item call isn’t happening on the server in dedicated mode. Is it being called on the server right? E.g., the client call then calls the server version of add item.
My suggestion is to do some of the blueprint networking tutorials to better understand how this all works, and maybe some general tutorials on blueprint.
You might also check the Unreal discord channel, and try to get more immediate help there.