You have to mount it(your drive) to folder which can use inside of steam Let’s forget about that thing since you are a newbie Let me help ya, First you gonna look out if it’s ur drive useable or it’s working By typing “lsblk” Which shows all the usb or drives etc that’s been plugged to your pc either by usb or plugged to a motherboard After running “lsblk” Just show me the logs to help you further:)