Why do I not have permissions to access EasyRoutes?

When you or one of your Shopify Staff accounts see the following error message:

It indicates that the particular Staff member does not have the necessary permissions.

To resolve, review the staff member's permissions:

Shopify Settings > Users and permissions > (click on staff member)

... and verify either Manage and install apps and channels (for all apps) or at least EasyRoutes Local Delivery is checked.