If it's a fully shared (controlled by all) calendar, I would choose Can edit.
That does not answer the question
It is a normal user, the admin account. That went to their calendar and clicked new calendar. They then shared it as shown.
Then I don't understand the question - I said - choose "Can edit" that's one of the choices you showed as an option.
WTF does "Can Edit" mean? Is it actually the most open access? I have no idea.
It's all hidden from the GUI now as far as I know but higher access levels still exist. The only thing I've actually run into people trying to use that requires it is messing with categories.
You have to be a Publishing Editor or Owner to work with them.
I usually end up assigning those for users using PowerShell when the need arises.