name each area you draw has a name input, If you want to add a category like a dropdown, you will have to edit multiple files.
in DataModel.cs add a string category variable or an enum:

Then in UIBaseItem.cs add a getter/setter to access your dropdown or inputfield, example with the Name input:

Edit the GetData() and SetData() methods to add your new category variable
Open the UIRoomItem_Prefab Variant prefab, add your dropdown or input field and link it in the script UIRoomItem

You will have to populate your dropdown with values by code as well.
I probably forgot steps but this is the main process.