I’m a bit lost still – are you using the built-in CSV import/export mechanism or a 3rd party plugin?
With the built-in product CSV import/export, I’d suggest the best way to start is to create one complete product of your own, export that product into a CSV file, and use the result as a template for your other products.
For instance, below is an image of the result of doing that on a sandbox site. Excess columns have been removed, leaving only the minimum required ones. Notice the “Type” column – it’s where the type of product is specified, and in this case it has a value “external”.
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Copy the values above into your own spreadsheet, export it as a CSV, and import it into your store to see how if it works for you too.
If we’re still not on the same page, perhaps include a few screenshots to illustrate. You can upload screenshots to your media library and share the link with us, or use a service like https://droplr.com/ https://www.getcloudapp.com/ to share a link to the image file.