Spent some time setting up a new laptop today and saw this error: PowerShell is required to use the Deployment Workbench. Found that to be weird considering I JUST used powershell to install MDT. Turns out I had forgot to set the execution policy back to RemoteSigned. Today, I learned: Powershell needs to be set to RemoteSigned the first time you run MDT.
Set-ExecutionPolicy RemoteSigned –Scope CurrentUser