Hi Yasar Shaikh ,
Welcome to the Microsoft Q&A Platform. Thank you for posting your query here.
You must provide an eligible license for each user that accesses Azure Virtual Desktop. The license you need also depends on whether you're using a Windows client operating system or a Windows Server operating system for your session hosts, and whether it's for internal or external commercial purposes.
Please follow this link for your reference: https://learn.microsoft.com/en-us/azure/virtual-desktop/licensing#eligible-licenses-to-use-azure-virtual-desktop
Verify that the Azure AD configuration is correct, and the users are properly synced with Azure AD.
Check if there are any conditional access policies that might be blocking the users from accessing AVD with their Azure AD accounts.
Authentication issues, such as password or MFA problems, that might be preventing users from signing in with their Azure AD accounts.
If you have any further queries, do let us know.
If the answer is helpful, please click "Accept Answer" and "Upvote it."