Notes and Clients/Contacts automatically sync instantaneously in the background. However, if you've been asked by the support team to initiate a force re-sync, make sure that you've not added any new contacts to eNoteFile in the last 15mins to make sure that the sync runs as expected.
Go to Notud ➡ Settings ➡ Force Contact Synchronization
You'll receive an email and a bell notification in Notud when the sync has completed. If you have a failed notification, make sure that you wait 15mins before trying again.