Created an 0365 Group for Shared Calendar; can't access it

Hi All: 

I created an O365 Group through the 0365 admin (created a group) for one of our departments and set myself as owner. My intent was to use this space as a shared calendar. I was able to access the calendar on my outlook (both web and desktop) however it won't let me modify the calendar, saying I don't have access, or share it? 

I know there is some quirk that is preventing me from doing what should be straightfoward. I've tried making myself a member, clearing the cache, restarting, as well as some other remedies. Any ideas?