You need a valid PR card to apply for a SIN at this point. To apply for a PRTD you can use your current passport and include copies of your parents PR and citizenship documents. IRCC can cross reference the information from there.
https://www.canada.ca/en/immigration-refugees-citizenship/services/application/application-forms-guides/guide-5529-applying-permanent-resident-travel-document.html
https://www.canada.ca/en/immigration-refugees-citizenship/services/application/application-forms-guides/guide-5529-applying-permanent-resident-travel-document.html