I would clear out all of the array elements on the player inventory, add one empty one and then drag an ‘inventory_slot’ resource into it, as that is the type of resource that array is wanting. If you drag in an ‘inventory_item’ resource into it, you will get the type mismatch.
so then you need to drop a resource that is an inventory_slot object type, so if you don’t have that setup, you’ll want to make those. Then in those, you will assign the Name and Texture like you see here: