...
If you don't take this step, you may get 404 Not Found error in Koongo Connector. Is is NOT a bug of connector but known limitation of Magento.
Enable Flat Catalog
Koongo Connector uses Flat Product and Flat Category data, so please make you sure you have enabled these two settings. You can enable Flat by clicking on the link in the notice or navigate to Stores -> Settings -> Configuration → System → Catalog → Storefront:
...