Hi Stephane,

Does this article clear up the air?

https://support.okta.com/help/s/article/Login-to-SharePoint-fails-after-federating-with-Okta

If not, any chance your tenant name and main domain name is different? For example my company's primary SMTP domain is @name.com, but my tenant name is @name2.onmicrosoft.com. This was the case in my company's case and we had to do some very strange manipulation to get it to work. I actually found the answer within this community but it's been awhile and I can't seem to locate it anymore. It was a bit of a manual process but worked flawlessly. I wish I could locate it to be more helpful.

Hi Stephane,

Thank you for posting on our community with your question! My first port of call would be to check the immutableID on the assigned account within the Okta profile for Office 365 and make sure that matches against their account on Office 365. This can be a great way to quickly establish the accounts are indeed matched up between the two parties.

As for that error specifically, Van Huynh has supplied a great potential solution, further digging into the error, it does look as though it's a form of naming convention, another potential flaw could be the application name it's self: https://social.msdn.microsoft.com/Forums/sqlserver/en-US/f494fb5b-cbdd-42c8-9d0f-d44e3c9ed44e/aadsts70001-application-with-identifier-was-not-found?forum=WindowsAzureAD

Review the above and see if this helps as well,

If all else fails, please do raise a ticket to Okta support and we will work closely with you to try and determine the cause of the issue.

Thank you,

Christopher Tomiak-Gough