mac client to windows server over openVPN

I'm trying to use a spacenavigator controller from my old 2010 mac (high sierra) laptop connected to a windows 7 server at office through Microsoft Remote desktop over OpenVPN.
I couldn't find any instruction on how to configure and forward ports for this kind of connections...
Sorry for the newbie question, but should I setup anything on the VPN before trying to correctly operate VirtualHere ?

Actually the Mac client says that no server is found and the icon "USB Hubs" does not expand to show any of the USB controllers attached to the system: Is this a client malfunction or could it be due to the fact that no server is seen?

The client log is:

2021-03-16 10:56:51 INFO :VirtualHere Client 5.1.6 starting (Compiled: Mar 4 2021 17:31:20)
2021-03-16 10:56:51 INFO :Client OS is macOS High Sierra Version 10.13.6 (Build 17G14019)
2021-03-16 10:56:51 INFO :Using config at /Users/roberto/Library/Preferences/vhui Preferences
2021-03-16 10:56:51 INFO :IPC available at /tmp/vhclient
2021-03-16 10:56:51 INFO :Auto-find using Bonjour - on
2021-03-16 10:56:51 INFO :Auto-find using Bonjour SSL - on
2021-03-16 10:56:51 INFO :SSLReverseLookupService listening on port 7572
2021-03-16 10:56:51 INFO :ReverseLookupService listening on port 7573 (IPv6 dual-stack)

The windows server log is:

2021-03-16 10:44:23 INFO :>>> Starting VirtualHere USB Server v4.2.5 (Built: Feb 15 2021, 14:04:22)<<<
2021-03-16 10:44:23 INFO :Using configuration G:\Down\IDM\Programmi\config.ini
2021-03-16 10:44:49 INFO :>>> Starting VirtualHere USB Server v4.2.5 (Built: Feb 15 2021, 14:04:22)<<<
2021-03-16 10:44:49 INFO :Using configuration G:\Down\IDM\Programmi\config.ini
2021-03-16 10:44:53 INFO :Server licensed to=unlicensed max_devices=1
2021-03-16 10:44:53 INFO :Server licensed to=unlicensed max_devices=1
2021-03-16 10:44:53 INFO :Listening on all network interfaces at TCP port 7575 (IPv6 dual-stack)
2021-03-16 10:44:53 INFO :Listening on all network interfaces at TCP port 7575 (IPv6 dual-stack)
2021-03-16 10:44:53 INFO :Found Low speed device [045e:0025] "Microsoft, Microsoft IntelliMouse ® with IntelliEye" at address 1
2021-03-16 10:44:53 INFO :Found Full speed device [0557:2213] "ATEN, DVI DualView KVM" at address 2
2021-03-16 10:44:53 INFO :Found Low speed device [045e:0025] "Microsoft, Microsoft IntelliMouse ® with IntelliEye" at address 1
2021-03-16 10:44:53 INFO :Found Full speed device [0557:2213] "ATEN, DVI DualView KVM" at address 2

Thanks in advance

Roberto