How to grab data from a fillable pdf that I attached it to the form through a iframe

To access the submissions filled in the fill-able PDF, kindly go to your account, "my forms" and select the form that created the fill-able PDF. Kindly check on the guide below on how to view your submissions form a fillable PDF.

https://www.jotform.com/fillable-pdf-form-creator/

I have also noted that the Fill-able PDf you have embedded in your form does not have submit button hence a user will fill the PDF but cannot submit it. You may need to re-create another Fill-able PDF.