Can't create or edit Family Calendar items in Outlook 2013

I've created a Family Calendar on Outlook.com, and I'm able to view and edit this calendar at outlook.com and in the Outlook for Android app on my phone.

In Outlook 2013, I can see the Family Calendar, but the New Appointment and New Meeting buttons are disabled. I cannot edit any existing appointments, and when I double click a day on the calendar to create one, this error is displayed:

You don't have permission to create an entry in this folder. Right-click the folder, and then click Properties to check your permissions for the folder. See the folder owner or your administrator to change your permission.

I right-clicked on the Family Calendar and changed the permissions for the Owner to full read and write, but that had no effect. I then added my own email user as an owner with full read and write, but that didn't work either. I tried creating a new email profile for Outlook, but still I do not have access to the Family Calendar. (I have full access to the default Calendar.)

How can I gain full access to the Family Calendar in Outlook 2013?

Thanks for your response, but I don't see anything at that link about changing from http to webcal. The parts about sharing aren't applicable, since the Family Calendar is automatically shared with all members of the Family group.

I've also looked at this on two other computers with different versions of Office: a laptop with Office 365 using the same email account, and my wife's computer using Office 2016 and her email account (which is a member of the Family group), and the results are the same - the Family Calendar can be read, but not edited.

- - - Updated - - -

Also, just to be clear for those who are unfamiliar - in the original post, when I wrote I "created" a Family calendar, what I actually did was add my family's email accounts to the Microsoft Family feature under my Microsoft account. Doing so automatically created a Family calendar and shared it with all members of the group.

Except - I discovered this eveing that my daughter can edit the Family calendar on her laptop. She is using Office Home and Student 2019. The Outlook 2019 Calendar interface resembles the interface on the mobile app and outlook.com, where you select which calendar to save the appointment to in the Create dialog, rather than saving it to whichever calendar you are currently "in."

It's curious that even Office 365 doesn't have this interface - and it's completely ridiculous that a shared calendar created by the system would be read-only on most (but not all) Office versions.

Not according to what I'm seeing. As I wrote in my previous reply, Office 365 and Office 2019 behave differently. I cannot update the Family calendar with Office 365 (or 2016 or 2013). I can update it with Office 2019 (and Outlook for Android).

Again, it makes no sense to me that the Family calendar Microsoft creates can be updated with some versions of Office, but not others.