One other thing: you mentioned having used e-mail to transfer the project. In most cases that won’t work well beceause a Scrivener project is really a folder with a bunch of files in it, and the e-mail attachment protocols are not designed for transferring complete folder structures. However if you zip compress the project before attaching it, so that it is all one single file, then you shouldn’t have any issues sending it. My preferred way of doing this is to use the File/Back Up/Back Up To… menu command as that has a built-in zip option, but you can also just locate the project in Finder and, with the project closed, right-click on it and choose to compress it. A .zip will appear a few moments later under a similar name.
Once on the second computer, double-click the .zip file, copy the “my project.scriv” folder out to a working area and open it with Scrivener. Since Windows lacks the feature of making special folders look and act like a file, you’ll see the whole folder structure. All you need to double-click on is the .scrivx file in the project’s main folder.