You don’t need to create a share that points to the USB drive. MBW offers the ability to configure USB port as a share.
If you actually plug a drive in the USB port, it becomes a public share by default. You can configure access privileges for specific users and groups by logging in to the web app using the administrator > Advanced Mode > Users > USB Share Permissions.
However, you won’t be able to share a specific folder on the USB drive: the whole drive is submitted to the access privileges you configure.
I’m talking about sharing with people on the same network here (so connected to your router/switch) and having a user account on MBW.
That being said, if your intent was to share the USB drive using Mionet (so remotely), you can do this by granting access only to the Mionet user installed on your MBW (in the same interface) and use the Mionet web client to share specific folders to specific people.
If this solved your issue, please choose “Accept Solution” from the post options and click the star to grant me kudos.