Hello Sophal Lee
Welcome to Microsoft Q&A Platform, thanks for posting your query here.
I can see Azure Serial console in Azure Portal, the serial console can be accessed by using the Azure portal or Azure CLI and is allowed only for those users who have an access role of Contributor or higher to the VM or virtual machine scale set.
Can you please check once on the prerequisites mentioned here: https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-machines/windows/serial-console-windows#prerequisites
Hope this helps.