To gain admin access over a portal, an existing admin must promote you. If you're not sure who the existing admins are, go to your organization, select the People tool, click All People in the top left of the page, then choose the Administrators group. Any of these users can add you as an admin. If they need help with the process of adding you, direct them to this article.
If the current admins have graduated or left the portal, contact the office that manages OrgSync on your campus. They are the only other users who can add you as an admin of the portal.