After I upgrade to the latest macOS Big Sur, I found that my company Anyconnect connection did not work. Unfortunately, I didn't do a proper uninstall by just moving the entire folder to bin. And, I emptied the bin.
Then, I tried to install Anyconnect and found an error message "The installation failed. The Installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance". Appreciate for any advice on this.