Hi Edy Lawson, how are you? Greetings from Brazil!
As I researched, labels are considered standard fields.
You can see by yourself in the documentation:
You will need to add the deal using the Make an API Call module, inserting the values manually, by their ID, separted by a comma.
As the documentation describes, you must first discover the ID from each label that you have. You can set up a test deal and check the ID of label per label by opening the URL https://yourcompany.pipedrive.com/api/v1/deals/{dealID}?api_token={yourtoken} in your browser, and look for “label” when pressing the CTRL+F in the json.
Now, what you have to do is send every field information on body, following the documentation here → Pipedrive API v1 Reference
If you have any custom field, you must use it’s ID that is a long string. This is easily found in the fields section in pipedrive, by clicking in the 3 dots in the custom fields section, like the screenshot below: