Do I need my own Amazon Professional account to use Amazon Channel?
Yes, Amazon Channel connects your online store to your Amazon selling account. You need an Amazon Professional Seller account (you can't use an individual account because Amazon doesn't provide a way for integration solutions to communicate with your account, only Professional accounts allow this).
Learn more about Amazon Professional Seller Accounts.
You are responsible for any Amazon charges - these are separate to any Amazon by Codisto app charges (Amazon Channel by Codisto paid plans) billed through Shopify.