do not use any cloudservice directly on the project. The RM-editors open the project file like a database (similiar to MS Access or Filemaker), and that conflicts with cloudsyncing to the point of a chance of destroying the data. you can use cloud for manual distribution, but never place the working project folder itself into the cloud.
That said, you can work on different maps at the same time and then combine them into a single project. Just make sure that all team members only work on their own maps before copying the mapfiles together. and you need to create the maps in the master-copy before distributing the files, the editor will not accept mapfiles above the map number it has created for the current project.