Hi,
One other information I've found is that you can do a bulk upload in O365.
So you can export a CSV file in a predefined by O365 format from IDM and import in O365.
Add several users at the same time to Office 365 - Admin Help - Office 365
This would create users with different passwords which need to be sent to the users.
Further you can continue to configure SAML 2.0 Single Sign-On for users using these guidelines
https://msdn.microsoft.com/en-us/library/azure/dn641269.aspx
Best wishes,
Fedya