To sync your Yellowdig grade to your school's gradebook, you typically must access Yellowdig through the graded assignment link on your course page (Canvas, Blackboard, Moodle, D2L, etc). This usually appears in the Assignments or Modules tab but may vary by your institution's setup. If you're having trouble finding the correct launch link and getting passback synced, try reaching out to your instructor or program coordinator to help.
In the meantime, any points you earn in Yellowdig will still count towards your grade. And your up-to-date grade will be passed back once grade passback is synced.
The video below shows a launch into Yellowdig from a Canvas 1.1 course page.
For a more detailed guide to how grades work in Yellowdig, see this article.