No. You are not required to work with an in-network contractor to receive a rebate through the Charge Ready Home program. However, the application process does differ slightly.
If you work with a contractor in-network, you will follow the Direct Participation Application Process. After you apply through the program database, you will receive an application ID that you will provide to the in-network contractor. From there, the contractor will claim your project and manage the rebate on your behalf.
If you work with a contractor that is not part of the Charge Ready Home Contractor Network, you are responsible for managing your rebate and you will follow the Customer-Managed Application Process.
Find more details on each process in Section 5 of the Implementation Manual.