Part design model question

Are our parts that we submit for the part design challenge judged by how they’re made in inventor?

Yes. The evaluation criteria is listed in the Judging Information section of the Make it Real CAD Engineering Challenge. According to the Evaluation Criteria and Additional Information, one of the elements the judges will evaluate is “Does the design work show skill proficiency using Fusion and/or Inventor? Is the software version clearly identified?”
This also ties in to the written description, because how your part is made reflects your design process, as the Evaluation Criteria also points out, “Written description: Judged on clarity, thoroughness, design process and description of use.”
Good luck!