Add Meeting Room Calendar To Outlook Office 365. This is the name that will be. Look for the ‘+add’ button on outlook calendar.

If you want to book meeting rooms in outlook calendar, you just need to. Log into your office 365 admin portal.
Once In There, You Will Need To Select “Mailbox Delegation” Then Add Yourself To The “Full Access”.
Select a suggested time slot, or manually enter a date and start and end times.
In The Navigation Menu, Click Room Management Then Calendar Integration.
You can access the admin portal from the waffle menu.
Sharing Office 365 Room's Availability To External Users.
Images References :
Alternatively, You Can Click In The Location Field And Select Browse With.
Once in there, you will need to select “mailbox delegation” then add yourself to the “full access”.
Select A Suggested Time Slot, Or Manually Enter A Date And Start And End Times.
Set up online meetings with teams.
Then, We Can Currently Share Room Calendar With External Tenant Via Steps: