Your Amazon seller account needs to be subscribed to Amazon's Professional plan in order for you to use any integration, including Trunk. To determine if you're already on the Professional plan, go to your Amazon Seller Central and on the top right corner, click Settings > Account Info and then look for Professional within the Your Services section. If you're on Amazon Handmade, you may already be subscribed to this free of charge.
When attempting to add an Amazon sales channel to Trunk, you'll be asked for your Amazon seller account's Seller ID and MWS Auth Token. It's pretty straightforward to obtain this!
Start off by going to the "Manage Your Apps" section within Amazon Seller Central depending on your seller account's region:
Once there, click Authorize new developer.
Then enter in the details below depending on your seller account's region.
If you have multiple seller accounts across different regions, you'll need to add each separately as different sales channels.
Brazil, Canada, Mexico, US
United Arab Emirates, Germany, Egypt, Spain, France, United Kingdom, India, Italy, Netherlands, Saudia Arabia, Turkey
Australia, Japan, Singapore
Click Next to continue to a screen for some terms and conditions. Once you agree to them and click Next again, you'll finally find your Seller ID and MWS Auth Token which you can copy and paste into Trunk to finish adding your Amazon sales channel.