Recently upgraded to macOS Big Sur 11.0.1. Also, changed from Eset to Norton 360. Now when I try to run VMWare Fusion latest version (I can't get to run enough to show the version) I get an error "Unsupported MacOS Version".
That normally means that you are on Fusion 11..
Fusion 11 does not work on macOS Big Sur. Only Fusion 12 works on Big Sur, because apple has made significant changes to their operating system.
If you are using VMware Fusion for personal use then you can now use a free version of VMware Fusion.
Perhaps the free Fusion Player 12 will work for you. (there's a link in the 2nd article)
Please note that if that link doesn't work and you are using Firefox, then try again using Safari or a private window.
We just purchased a license for VMWare 11.5 in August. Now after upgraded to Big Sur it's useless. Does it mean I have to pay for upgrade/license in order to use the product I only had for 3 months?
Please read the Technology Guarantee Program section of this article: https://blogs.vmware.com/teamfusion/2020/08/announcing-fusion-12-and-workstation-16.html
Easy to complain if apple changes the game and disallows kernel modules... thereby forcing VMware to use apple's hypervisor instead of their own...
Also seems that you missed that VMware released a FREE version of VMware Fusion that you can use.