Amazon Marketplace is an e-commerce platform owned and operated by Amazon that enables third-party sellers to sell new or used products on a fixed-price online marketplace alongside Amazon's regular offerings. To Connect Amazon Marketplace seller account you'll need to get Seller ID and MWSAuthToken,
Use the following instructions to authorize Asalta.
Under Apps & Services in top menu select Manage your apps, Click Authorize new developer button
Use Below Credential and Authorize Asalta's Developer account:
Check "I understand that I take complete responsibility for the acts and omissions of asalta regarding my Amazon selling account and
hereby direct Amazon to allow asalta to access my Amazon selling account." and Click on Next button.
At this moment MWSAuthToken will be generated, don't close the screen and copy the Seller ID, Marketplace ID, and MWS Authorisation Token
In Asalta's Amazon Connect Screen Paste the copied credential and Click on Connect to Amazon Marketplace button