From the menu in the Client, click on Open and choose Replication and Sync:
If you've docked or pinned your Bookmark Bar, the Open button won't appear; look for the Replication and Sync Icon in the docked bar:
You should get a screen that looks like this - do a right mouse click on Synchronize Contacts, and choose Replicate Selected Application.
You don't need to click Start Now - once the replication has run for Synchronize Contacts, you're done.
If Synchronize Contacts can't be enabled go to File - Preferences - Contacts and select Enable "Synchronize Contacts" on the Replication and Sync tab (Required for Contacts delegation and iNotes Contacts synchronization)