Thank you for reaching out to the PowerSchool Community.
At this time, school staff can not upload the documents for the parent portal. We do have an enhancement request in the PowerSchool Ideas Portal for this feature. I recommend you consider adding a vote to SIS-I-12564 for the PowerSchool team to review. Submitting an Enhancement Request will guide you through searching and voting in the Ideas Portal.
I recommend reaching out to your PowerSchool product administrators in your district for the process that they have in place for loading the NWEA MAP Family Reports to PowerSchool.