Outlook Calendars for Confluence supports to embed Resource and Room calendars directly into Confluence. However, due to restrictions in Office 365, accessing rooms requires an admin consent and is not enabled by default.
Working with rooms requires the Office Permission: Places.Read.All
Steps to enable Room calendars
📂 Open the following URL, login as Office admin and consent the permission for the organization.
Afterwards every user can open room calendars on his own.