Launch Terminal
Run curl https://raw.githubusercontent.com/mtan93/googledrivefilestream-bigsur/master/fix-bs-filestream.sh -o ~/fix-bs-filestream.sh && chmod +x ~/fix-bs-filestream.sh
Run the script by pasting ~/fix-bs-filestream.sh
Then allow the dfsfuse kext under System Preferences > Security & Privacy and reboot your Mac.
Run the script again by pasting ~/fix-bs-filestream.sh
Finally the mount should pop up on the desktop!