Project syncing in a Collaboration project is automatic by default, but you can manually control check ins and check outs and their options in the Collaboration tab.
Share Project: Share a Plant Project to BIM 360 Team for collaboration with team members.
Check In: Manually check in a new or existing active drawing to BIM 360 Team.
Check Out: Manually check out the active open drawing from BIM 360 Team.
Undo Check Out: Ignores any changes made to the open drawing and cancels the check-out.
Options: Displays the Options dialog box in which you can specify settings about synchronization, check out, check-in and local workspace settings.
Attach: Attaches a project drawing file that exists in BIM 360 Team.