Installing the game on another or external drive will work just fine, the issue here is that you just copy and pasted the files. What you should do instead is start the installation on another drive and then cancel it. Once you have some of the files installed, then you can copy and paste the files. However, that would require a process with a lot more storage space. It would be in your best interest to just uninstall the game and then install it from scratch again to prevent any potential issues down the road.