@AndrewIles,
Splunk Add-On for Microsoft cloud services v3.0.0 is not supporting Office 365 features from this version thats the reason you unable to find office365 tab over there.
Can you please confirm which version of Microsoft cloud service add-on you are currently using?
So if you want to collect and configure data for Splunk Add-On for Office 365 Add-On, then please download the office 365 Add-on from this location: https://splunkbase.splunk.com/app/4055/
https://www.splunk.com/blog/2017/07/27/splunking-microsoft-cloud-data-part-1.html , this steps useful when you are using older version of Add-on i.e. 2.1.0 of Microsoft cloud services.
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