Hi,
Perhaps you've solved this by now since you posted this quite a few days ago! But yes, you will need to either have admin access and make your own account a Planner, or have an existing admin make your account a Planner. Anyone with Planner access can see unpublished plans, but once they are published other users will be able to see them, regardless or Planner rights.
Here are two links for more information:
https://techdocs.broadcom.com/us/en/ca-enterprise-software/agile-development-and-management/rally-platform-ca-agile-central/rally/using/using-portfolio-items/portfolio-item-planning/capacity-planning-page/working-with-capacity-plans.html
https://techdocs.broadcom.com/us/en/ca-enterprise-software/agile-development-and-management/rally-platform-ca-agile-central/rally/using/using-portfolio-items/portfolio-item-planning/capacity-planning-page.html