The Microsoft Office Configuration Analyzer Tool (OffCAT) was removed from the Microsoft Download Center on June 11, 2018.
The Outlook scanning functionality of OffCAT is available in the Microsoft Support and Recovery Assistant for Office 365 (SaRA) tool. SaRA offers several improvements, including the ability to identify and fix specific issues in Outlook, Office Setup, OneDrive for Business, and several other Office programs. You can use the SaRA tool is used to scan for issues in Outlook.
For more information, see How to scan Outlook by using the Microsoft Support and Recovery Assistant tool.