You have two options in how you use Office 365 resource calendars.
Grant permissions to a OnceHub User's calendar
Ensure that your Exchange Administrator grants you full read/write permissions to the resource calendars you need to use.
Add the relevant resource calendar(s) to your Outlook Calendar.
In your OnceHub account, on the lefthand side menu, click the Booking pages icon. Select the Booking page that you want to use and configure the resource calendar settings in the Associated calendars section.
Follow the instructions in the Resource scheduling article.
Create a OnceHub user solely for that resource
In the Associated calendars section of that User's booking page, the resource calendar will be the main booking calendar for that scheduled meeting.
You can also add the User to a resource pool or to a panel meeting as a panelist.
When creating a panel meeting using a room or resource, we recommend you select the resource calendar User for the Booking assignment field. Add other members of the panel under the Additional team members field.
If you decide to select a different User for the Booking assignment field, making that User the main panelist instead of the resource calendar User, the behavior may not be optimal.
In a panel meeting, the main panelist is the User selected in the Booking assignment field. The calendar event is owned by their calendar and all other panelists are added to the event as guests. Due to the way Microsoft coded their resource calendars, a resource calendar added as a guest to a calendar event will not update when an event is canceled. This will leave a blocked event on that resource calendar at the canceled time.
However, if the resource calendar User is selected in the Booking assignment field, it becomes the main panelist and owns the calendar event, adding all other panelists as guests. If the event is canceled, the cancellation will reflect on all calendars and the time will be freed.