ActiveCampaign hidden fields to appear in Elementor Form
By default Elementor doesn't list to map hdden fields in Elementor Form
You can't map your form field to a hidden field in Elementor...
You can resolve this in two ways
change all the custom parameters from ActiveCampaign to text from hidden. They will immediately will be mappable.
edit elementor code (single line edit) wp-content/plugins/elementor-pro/modules/forms/classes/activecampaign-handler.php:131. Add hidden => 'text' as shown in the image.
After you are done either of those, you will be able to map the fields just fine (see the image)...