I have ubuntu installed in my work laptop and windows installed in my virtualbox. I installed windows in virtual machine so that I can download origin games on it. I want to copy those origin game files form the windows virtual machine to my ubuntu main host so that I can copy it from ubuntu to my gaming pc later. How should I do it?
Install sshfs and winfsp on Windows guest and mount host $HOME directory as a drive and copy files there.
Installing guest additions for VBox should sort you out.
After install, just make a shared folder in the VBox settings for your VM and it will show as a normal drive in file explorer.