I'd give my kingdom for a Cisco-compatible VPN client written by anyone else, even if it was (yuck) Microsoft. (I didn't stumble across the reinstall trick until much later, after I'd replaced both systems with a MacBook Pro and Fusion.) And the Windows client on the Dell had its own problems that I never figured out. I first encountered it on a G4 Mac Mini - the Mac client got confused by the Firewire connection to my Dell, so I had to turn that off to use the VPN. This "can't find a network interface" nonsense isn't unique to Fusion, OS X or even Intel systems. Given my own experiences with Cisco's lovely VPN client (had to do another repair job inside the VM on Monday), I wonder if reinstalling it while the VM is running would help in your case. My solution is to: 1) suspend my VM, quit VMWare 2) sudo ifconfig vmnet1 down sudo ifconfig vmnet8 down 3) launch VPN client and connect 4) launch VMWare. Basically, if I run VMWare before I run the Cisco VPN client, I cannot then launch the VPN client (it fails with an error 51: can't find a network interface).
Make sure you have further understanding on your Mac computer and follow steps below to learn how to clean uninstall Cisco An圜onnect VPN Client on Mac. But beware that just by dragging Cisco An圜onnect from the Folder into the Trash bin is far away from enough. If you want to uninstall the An圜onnect Client on macOS Catalina, but without using a particular uninstaller, then it's also possible to do it manually.