Ok, So my host OS (Windows 10 Pro [21H1 19043.1320]) was the problem. I followed the instruction in KB2146361. But the key is: completely disable Hyper-V on the host. So I disabled Hyper-V on my host OS.
Then I launched my Workstation Pro 16.2.0 (build-18760230) and started my Windows 10 Pro (21H1 19043.1320) VM, I disabled Hyper-V; I installed Docker; and it worked.
I've only ever had Workstation Pro 16. Now my RHEL7 & 8, and Windows all run Docker and Kubernetes with no problems.
What is VBS?