Hi Zeng Aaron & thx for join me at Q&A platform,
There are two separate things to look at here: Azure for Students eligibility verification and the Microsoft account sign-in issue.
Ur approved GitHub Student Developer Pack is useful evidence that GitHub has verified your student status, but it doesn't automatically guarantee Azure for Students activation. Microsoft performs its own eligibility and account checks.
The message "Our systems are detecting a problem with your account and are unable to validate your access" suggests that Microsoft's account verification process is blocking the activation. Unfortunately, that message doesn't tell us whether the issue is related to student eligibility, an existing subscription, or an account risk check.
The AADSTS16000 error may be a separate identity-selection problem. It can occur when Microsoft Entra ID can't resolve the correct account identity for the sign-in request, particularly when multiple Microsoft identities or sessions are involved. It doesn't necessarily mean your student application was rejected.
I'd try opening a private browser session and signing in directly with the Microsoft account you intend to use for Azure for Students. If your college email is also associated with a school-managed Microsoft Entra account, make sure you're selecting the intended account rather than switching between personal and organizational identities.
Also, check whether you've previously activated Azure for Students using another Microsoft account. The student offer has eligibility restrictions, and creating another account won't necessarily bypass an existing eligibility record.
If the same verification error persists, this needs Azure subscription and account verification support, rather than Azure Managed Applications support. Microsoft Q&A moderators can't inspect or clear account verification restrictions from the forum. If the Azure portal prevents you from opening a support request, use the Azure subscription sign-up support channel and explain that the verification failure is also blocking access to Azure Support. Include the exact error, the timestamp, and any correlation or request ID displayed with AADSTS16000.
I'd avoid repeatedly creating accounts or attempting new registrations until support has checked the existing account status. Ur GitHub Student Developer Pack approval is worth mentioning in the case, but the key is getting Microsoft to identify which Azure verification check is failing
rgds,
Alex
p.s. if my answer is help - pls mark it as an answer