Sync Microsoft 365 with icloud calendar

Ive been using outlook for years with my icloud calendar and all has been well.

Just paid for 365 premium and the emails come over but the calendar is missing. I use the icloud calendar as default.

If i add an account because my icloud has the same email as my defauly email ms account it says it is already there.

I've logged in and out of cloud as this used to be problem, but no where either on my pc or iphone is there an icloud calendar to view or add??