If the path to 86Box isn't correct and you try to configure a VM, it'll produce an error stating "This virtual machine could not be started." followed by an Exception message:

I realized after going through Settings that 86BoxManager uses a path to locate 86Box rather than just being in the same directory (I had unzipped the two into a desktop folder). It would be beneficial to new users to either 1) update this error to match the same error displayed when trying to start a VM ("Cannot find 86Box.exe. Make sure your settings are correct and try again.") or 2) you could also check if 86Box.exe exists in C:\Program Files (x86)\86Box\ and then set the path as such otherwise prompt the user for it's location on startup.