PowerSchool Enrollment forms can receive any file type in the document upload fields. However, only one file can be uploaded per document field. I recommend ensuring that the file size of the document you are uploading does not exceed 25MB.
It is possible that the document you are trying to upload may not be uploaded due to a required field missing information. Some of the commonly overlooked fields in the form are the priorities of the emergency contacts, primary phone number for the contacts mentioned within the form.
I have attached an article here that should help walk you through a few troubleshooting steps to upload documents to your forms.