Once the Connect flow has been completed, Connect will respond with the session_complete object. The data payload will include your original callback_uri with the fp_cot query parameter carrying the original connect_token. 
{
  "connect_token": "cot_6587fa4362341be5b524de3b",
  "route": "session_complete",
  "direction": "IMPORT",
  "live_mode": false,
  "data": {
      "callback_uri": "https://webhook.site/4623e56fc5c1?fp_cot=cot_6587fa4362341be5b524de3b"
  }
}
Return your customer to other pages of your app and get your backend systems to go to exchange-a-connect-token endpoint to obtain a permanent ID (location_id) that you will use to interact with FlatPeak API. Save location_id permanently in your system in reference to your internal customer address object