The PowerSchool Community is a great resource if you have any changes to be made while completing fields within the enrollment form. Each district, however, has a different registration process and can provide the best steps to move forward when enrolling students.
If the deadline for the form submission has passed and you were not able to complete registration, I suggest informing the district directly because they would be able to assist you to proceed with the registration.
You can check out the FAQs related to the enrollment process here.