Hello,
You cannot use a Domain Controller on a VM in Azure because Azure uses SDN (Software Defined Networking), hence, does not support protocols such as LDAP / Kerberos. If you want to join the cloud hosted windows 10 workstation to a domain, use the Azure Active Directory Domain Services (Not Azure Active Directory). This will be implemented on a VNET. And you can change the DNS settings of the window 10 workstation VNET to point to the AADDS instance you created earlier. You'll need to setup VNET peering too.
Thank you very much.