Right, the taxonomy creation feature yet not available in the plugin. So you could add a new “Action Hook” field and add a new text input field and using the wpuf_add_post_after_insert action hook, you can create the taxonomy.
I found out only that this is not an option after i just bought the plugin. I think it should be a standard inclusion in this plugin. It is just a pity I couldn't read all the forum post as I need this in my requirements. I think the plugin is far from complete
I would have thought it being a standard as it is common to have a custom taxonomy for a custom post type. and tags are normally freely choosable not like categories which are normally well defined so a dropdown or checkbox will work for those, but they won't work for tags. So yes for me it is one big thing missing to make this plugin incomplete.
Your current solution only allows a dropdown/checkbox and even that is not working nicely on custom tags (not categories)