While I have already found a solution (and with it found out that the software doesn’t even work in windows xp) the only way to download Boxes that I could find was through flathub, which doesn’t allow usb devices for some reason. What does work is that I can just put all of the files I want transferred into an iso file and mount it to the VM.
Also, if there is a way to install Boxes outside of flathub, I’ll have to check it out tomorrow because of late it is for me right now.