Hi, John154,
You cannot export a Mac iMovie project itself (as opposed to a shared-out movie from a project). Projects must reside in an iMovie library. So, you can create a new library, put the project into it, and then transfer the library along with the project, to another drive. In your case you would need to copy the library with the project in it to a USB Thumb Drive (or other external drive) that is formatted Mac OS Extended (Journaled). Then you could send the USB drive to your business partners, who could plug it in to a computer and access and edit the project. They would need to have Mac computers and also be running the exact same version of iMovie that created the project.
-- Rich