User gets an error stating "Not able to create or edit a plan? Most likely you don't have planning permissions". Except the user is an editor/admin for the project. Why do they get an error?
The capacity planner page has a separate permission associated to it called "Planner". If it isn't checked for the user then they will get this error.
A workspace or subscription administrator can edit the user and check the Planner box to give the user access to capacity planning