If your district has issued you a Snapcode, this indicates that you will need a specific link provided to you by your district to access your form. I would suggest reviewing your district's website for the specific link for Returning Students or accessing your enrollment forms through the Parent Portal by following the steps mentioned in this article: Accessing the Form using PowerSchool Parent Portal. When you access the form you will be prompted to enter the Snapcode provided to you to proceed with your application.
If you cannot locate this link, I would suggest contacting your school district directly to receive it. You can check out the FAQs related to the enrollment process here.