The downloading, installing and syncing of Magento 2 is exactly the same as Magento 1. By downloading the extension and entering the API key to sync, Pathfinder will connect to your Magento 2 store and import all your current store info like the products you offer, the created orders, cart info etc.
After you've downloaded the Magento 2 Extension, you need to connect your Magento 2 store, with the API key, provided by Pathfinder, and place it onto your Magento 2 Admin panel. To do this, you need to go to Stores on the left dashboard panel, then click Configuration. Make sure the Store view is set to Pathfinder. Scroll down on the menu to find Pathfinder tab, and click Settings. Here you'll be find the API key insertion place, where you could put the given key. Enter the provided API key, select the customer attributes you would like to sync with Pathfinder and hit Save Config:
If done properly, all synced data will be visible on the admin panel and you can view your products/stores inside your Pathfinder account, in the Marketing Calendar.