Thanks for considering the steps given by my colleague and for providing additional details of your concern, @jonisenhower.
To get the classes to be integrated into your webstore, I'd suggest looking for a third-party app that will help you with the process. You can browse through our QuickBooks Apps store to find the app you need. Let me guide you how:
Feel free to visit this article for videos and guides in assisting you with any of your QuickBooks Online (QBO) tasks: QuickBooks Online - Video tutorials. It includes different categories and topics for QBO.
I'm always around if you have any other QuickBooks concerns. Don't hesitate to post again here. Have a good one.