If we look at the client side of Workplace Join process it says that we should log on with Microsoft account, but I've never seen it mentioned that Microsoft account is a requirement for Workplace Join. Recently I performed server side setup for Workplace Join on my test server using the following steps:
"Why Windows Server 2012 R2: Step-by-Step Workplace Join, Bringing Peace of Mind for BYOD"
Unfortunately I was not able to perform Windows 8.1 VM join following those steps:
Walkthrough: Workplace Join with a Windows Device
Could it be because of using local instead of Microsoft account? Am I missing something else here? Network connectivity between VMs is checked.
Workspace join does not require a Microsoft account. This service is based on the concept of claims, and is implemented using the Windows Application Proxy services which is a version of the Microsoft AD Federation services, designed specifically for the DMZ, and enhanced with the support for the Workspace Join.
This service is then published using the special DNS records which allow your clients to find the server. The login process is based on UPN; which leverages the Domain Name portion of the UPN to route your client to your WAP server.
In your case you do not state the error, DNS is important, and ensure that you have the correct DNS entries added to identify to your client where your workspace join is hosted.