Does this plugin work with any Amazon seller account?
Amazon doesn’t allow access to their marketplace API using an standard buyer account or an individual seller account without monthly fees. In order to use WP-Lister for Amazon you need to sign up for a professional seller account which is $39.95 per month.
If you are an individual seller and would like to use WP-Lister for Amazon, you can upgrade your account to a Professional Merchant seller account from the “Setting – Account Info” page in your Seller Central account.
See this page for more information.