How to set up Shared Folder in Virtualbox (Whonix guest)?

Question

linux

I say right away how to set up Shared Folder in general cases, I know, I have never had problems with this with any guest hosts. And here at all in any.
Host - Ubuntu 16.04. Guest - Whonix Workstation. It already comes with VirtualBox Guest Additions installed. Users are also added to the group.
There is a brief mention in the official doc
https://www.whonix.org/wiki/VirtualBox/Guest_Addit...
If you are using a default Whonix-Gateway or Whonix-Workstation, please press on expand on the right side.
1) Power off the virtual machine.[3]
2) Go to VirtualBox -> Machine -> Settings -> Shared Folder -> choose a folder -> folder name shared. Choose mount automatically. Press OK.
3) Power on the virtual machine again
4) Done. Files you drop into /mnt/shared in the virtual machine will end up in your chosen host shared folder and vice versa.
So I do:
1. I turn off the virtual machine
2. I go to the Shared Folder settings, select a folder on my host, I call it shared (I tried different names, it’s not clear why there is such a binding)
3. I turn on the virtual machine.
4. I drop several files in the Whonix virtual guest for testing into the /mnt/shared folder. And I don't see shit on the host. The same thing in the opposite direction - those files that I put on Ubuntu in the shared folder are not visible from the guest.
Well, what kind of nonsense? Where am I doing wrong?