Cisco Anyconnect

I have macOS Big Sur 11.3.1 running. My Cisco Anyconnect client verion 4.9.04043 didn't work. While I was trying to re-install the app, I did not do a proper uninstall by just moving the whole directory to the recycle bin.

I followed the advice from https://community.cisco.com/t5/vpn/how-to-remove-cisco-anyconnect-mobility-from-osx-big-sur/td-p/4303190 after I realized that I could not reinstall the app at all.

Now, I managed to start the installation but got the an error "The installation failed. The installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance"

I checked the /var/db directory but could not find any left-over files as suggested in https://discussions.apple.com/thread/250505059

Any advice?