Explanation/Reference:
Explanation:
Microsoft Remote Connectivity Analyzer is a website offered by Microsoft for testing remote connectivity to server services such as Exchange Server, Skype for Business Server and Office 365. In this question, we need to run the Free/Busy test in the Microsoft Remote Connectivity Analyzer website.
The Office 365 tab on the Remote Connectivity Analyzer has several options for performing different tests regarding Office 365 connectivity. These tests include:
Office 365 General Tests

Microsoft Exchange ActiveSync Connectivity Tests

Microsoft Exchange Web Services Connectivity Tests

Microsoft Office Outlook Connectivity Tests

Internet Email Tests

Mail Flow Configuration

Free/Busy Test

The description given for the Free/Busy test is as follows:
"This test verifies that an Office 365 mailbox can access the free/busy information of an on-premises mailbox, and vice versa (one direction per test run)."