To download your product catalog, you must access it from the individual Reviewbox services. For example, if you want to see all the listings in Reviewbox, go to the Reviewbox -> Products tab.
Under Select Download, choose the Current View option. The Current View allows you to download the information that is currently displayed in the grid page into a CSV file. If you want to download your entire catalog, make sure that you clear all filters and view all custom fields before downloading the Current View.
If you have different products loaded in the different services, be sure to download the Current View from Pricebox, Copybox, and etc.