Thank you for reaching out in the Community!
If you need to create your PowerSchool SIS Parent Portal, please refer to this article, How do I log into PowerSchool, to setup up your account correctly. The access ID and Password helps link students to your Parent Portal account, it is not the same as your Parent Portal credentials. You will have to set those using the Create Account button on the Parent Portal page. You can refer to this article: Adding Students to the Parent Portal to add a student to your Parent Portal.
Since the Parent Portal accounts are managed and handled at the school district's end and are stored on their servers, you can also try reaching out to your school district directly who should be able to help you with a solution.