A list of Plant Collaboration projects you have access to is displayed. The drop-down list at the left (above the Plant projects) displays the Autodesk Docs accounts you have access to. The drop-down list at the right displays the Autodesk Docs project folders you have access to within that account.
The project opens from Autodesk Docs. Project information is copied locally so it may take some time to open the project the first time due to initial syncing or downloading of the project.