The procedure is quite simple
1. Go to the calendar tab of your Outlook
2. Click on "Add a calendar" in the upper ribbon and then "From the address book"
3. Search the meeting room in the list
4. Highlight the meeting room by clicking on it once and then click on "Calendar"
It will add the meeting room in the box next to the "Calendar" button. Then click on "OK" in the bottom right corner of the window.
5.The calendar is now accessible in the calendar tab of your Outlook.