Something here might help:
How do I register to use the VLSC
https://learn.microsoft.com/en-us/licensing/sign-in-faq#how-do-i-register-to-use-the-vlsc
If nothing in the above link hleps, I suggest you contact the Volume Licensing Service Center (VLSC) support over here:
https://learn.microsoft.com/en-us/licensing/contact-us
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Best regards,
Leon