The task was to integrate an ERP system (more specific Hotel management system called Hotellinx) which is (and should always stay or be) a single source of truth (SSOT) for the products they have and administer. If you want to sell these products from another system like a webshop you need to transfer the data there to showcase your goods to customers. Another way of explaining that is to say the webshop is only to make a purchase but all the data is stored to the ERP system or SSOT.