Thank you for posting your query on Microsoft Q&A. I am reviewing this and will get back to you with further inputs.
Update1:
To resolve the error, sign out from the active session and sign in with a new incognito window or any different browser.
Kindly refer to below doc for similar issue and TSG:
Error AADSTS50020 - User account from identity provider does not exist in tenant
If this does not work then please validate the following:
- See if you are logging onto correct directory on your tenant:
- External collaboration settings:
- Sign in to the Azure portal with Global Administrator permissions.
- Browse to Azure Active Directory > User settings.
- Under External users, select Manage external collaboration settings.
- On the External collaboration settings page, select Guest user access is restricted to properties and memberships of their own directory objects option.
- If you are an administrator, you can also try to dismiss the user risk after ensuring that the risk assessment was a false positive.
Update 2:
Seems like you were using a free version of Azure AD/Entra ID. Since Azure AD is now Microsoft Entra ID,
The free edition of Microsoft Entra ID is included with a subscription of a commercial online service such as Azure, Dynamics 365, Intune, Power Platform, and others.
So either you may get one of the above mentioned subscription or you needed P1 or P2 subscription: https://www.microsoft.com/en-us/security/business/identity-access/microsoft-entra-id#:~:text=The%20free%20edition%20of%20Microsoft,%2C%20Power%20Platform%2C%20and%20others.
Thanks,
Akshay Kaushik
Please "Accept the answer" (Yes), and share your feedback if the suggestion answers you’re your query. This will help us and others in the community as well.
Thanks,
Akshay Kaushik