Motion 5 sharing projects in process with others who want to continue working on it

I have a project in process where the mask has shifted. I want a co worker to look at it and try to fix the issue. When I shared it to dropbox, they could not open it in motion, I'm assuming because all the media files did not accompany it. How do I do that so they can continue working on the project and all that I have done is not lost?