Do you know why I can not find the following app "Amazon Marketplace Connector by Intuit" in the Apps center? I need it to connect Amazon Seller to my account.

Thanks for reaching out to Community, @amaury-debaynast. I'll share some information about the Amazon Marketplace Connector by Intuit in QuickBooks Online (QBO).

This app can be search and is available in the US region. For ROW, I suggest visiting this link to check if it is available in your region.

Otherwise, you can contact Amazon support to check if it can be integrated with QBO in your region.

You'll also want to search for another third-party app in the QuickBooks Online App Store that can connect Amazon seller to your account.

In addition, here's a compilation of helpful articles for the steps related to your business task while working with us: Help Articles for QuickBooks Online.

Please don't hesitate to reply if you have follow-up questions or concerns with third-party apps. I'll be glad to answer them for you. Have a nice day ahead.