I’m having a hard time finding any way to have eM Client read/sync the with Contacts.app on my Mac. I can’t anything in the app’s Settings, Accounts, or Contacts window related to accessing my existing contact, nor can I find anything in the online documentation about this.
I don’t sync my contacts to the cloud. They are on-device only for security reasons
Then you would need to export them out of the app and then import them manually into eM Client via “Menu / File / Import” where eM Client supports various different contact formats.