It is important to mention that private suppliers cannot be found in the Search Products section.
To to find the private supplier, you will need to use the 'Find Suppliers' menu from the Marketplace.
Please Click on Marketplace -> Find Suppliers and choose the Private Supplier you are looking for from the Advanced search options' Supplier menu.
You can see the pop-up window displayed upon trying to use a catalog that belongs to a private supplier in the below screenshot.
Here you can enter the activation code received from the supplier.
Once the code is entered, you need to click on 'Activate' to access the catalog.
Now you will be able to import the products in bulk as described in this article.
To find out where you can get the activation code from, please check the below article:
In case you have any questions or need assistance with our app, feel free to send an e-mail at firstname.lastname@example.org or contact us on our in-app chat.