File upload field on Keap forms

Does anyone know a way to add an “upload your file” form field to a Keap/Infusionsoft form?

The form will be used on our Wordpress website. I can build a form with an upload file field using Contact Forms 7, then use Zapier and Webhooks to feed the info into Keap. It works but I want to use a native Keap form on our site.

I’m a beginner when it comes to JavaScript and PHP. If anyone knows of some code I could modify to get this to work please let me know as this might be a good starting point. I see a “Hidden Field” option when building the Keap form. I think I can include any code needed there.