Description:
Invalid product quantity. Product listings must have at least one product with an inventory quantity greater than zero.
This means you left the quantity column empty or at 0.
Solution:
Quantity must be:
A positive number
Not empty
If you enter a decimal, Shop Uploader automatically rounds down.
For example, if you enter 8.5 it will be uploaded to Etsy as 8.
For more information about quantity visit the documentation page.