If I follow your instructions, I will stick to the following point:
PS C:\Users\h.eichmeyer> New-ClientVM -TenantName 'henetsystems' -OSBuild 2004 -NumberOfVMs 1 -CPUsPerVM 5 -VMMemory 8gb
Grabbing Autopilot config..
Creating VM: henetsystems_1..
WARNING: Cannot process argument transformation on parameter 'RefVHDX'. Cannot convert value to type System.String.
PS C:\Users\h.eichmeyer>