Hi there,
https://learn.microsoft.com/en-us/learn/certifications/
You can get the assessment can you taken from the above link
Windows Server 2019 Hybrid Technical Assessment can also be taken through a different site or from other Partners.
https://partner.microsoft.com/en-US/support/?stage=1
You can contact MPN Support team directly as they are the one who facilitate the assessments.
Hope this Answers all your queries , if not please do repost back .
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