If you don't want or need inventory tracking in QuickBooks, then you can use a non-inventory item for all of your SKUs.
Make a non-inventory item in QuickBooks Online for all of your Amazon inventory. Give it a descriptive name like Amazon US SKUs.
You'll want to be sure to set your Income account.
Note: some plans, like Simple Start, may not have the following option below. If your non-inventory item does not have it, then you can skip this step. Otherwise, select it.
Check the "I purchase this product/service from a vendor" box and select the expense account you want associated with this item so that we can process transactions like reimbursements.
Then map that non-inventory item in SellerZen. We'll use this non-inventory item for all of your invoices.
Make sure to click on Save.