Import Plugin doesn't develop relationships

Hi everyone,
I was hoping to get some help with a plugin that my partner and I have been working with to bulk upload products.
Bulk Import Product Plugin

The plugin is great and works really well but it isn’t able to establish the relationship with vendors or categories:
When uploading the product, I have the option to select which text/number is the name, description, price, image etc. However, regardless of what we put in the field for the vendor/category, it doesn’t upload the product connected to a specific vendor. We have tried inputting the vendor/category ID or name into this field and it simply doesn’t work.

We are currently editing each product one by one to establish the relationship with a category or vendor, but it would be much easier to do this when uploading the products using the plugin.