If someone has added you as a collaborator you are able to download the scenario that person is working on and modify it in your own machine.
To do this, you need to go to File > Scenario > Add Scenario > Download from space
You can select a space from the drop down list or add a new one:
If you want to add a new one, you need to provide the space number, your e-mail and the space name. You can also add an image to identify that scenario.