It's possible to Integrate with Open Cart using a couple of php files and our Poller Interface - See Poller - Setup for more details
Typically you'll need to place a sub folder with the open cart directory
e.g. /API (public html is the root web folder but could be different depending on install etc)
Should be two files:
Index.php - Contains Logic to pull info from OpenCart DB
Mintsoft.php - Contains Definition of what an order should look like.
Two files are attached to this page. Was using PHP 7 so is using mysqli to connect to the DB.
Config is the same setup as Poller so please refer to that page for more details on that