An integrated threat protection solution designed to detect, investigate, and respond to cyber threats across Microsoft 365 services.
You are invited to start your assessment at multiple Defender for Office 365 resources on the Microsoft 365 Defender portal, although the centralized location to start your assessment is on the Assessments page at https://security.microsoft.com/atpEvaluation. You may have started the assessment without realizing it, but from the link above you can try to register for the assessment if the system accepting your application means that your assessment has not actually been processed.