There are no mailboxes in the local Active Directory Environment to Manage. Active Roles will only show Exchange Tabs or Exchange Properties if there is an Exchange environment to manage. There are no On-Prem Exchange mailboxes to communicate with.
Note: The Active Roles Web Interface will display the users Exchange tabs by design for O365 mail enabled users.
This is intended functionality and is by design for Active Roles Server. If there are no Microsoft Exchange servers (On-Prem) mailboxes for users, there will be no Exchange tabs present within the Active Roles MMC console.