Feed Preview is automatically opened after profile execution. It might be also opened by button Feed Preview at Export Profiles Grid. See image below.
Preview show first few products from exported feed file. Thus you can check exported feed XML/CSV/TXT file directly at your Magento backend.
You can also:
Koongo Connector provides you Feed Files specific to all supported channels and marketplaces. Feed Files are XML, CSV or TXT files containing all your product data. That means once you set up given channel in Koongo interface you need to upload the generated Feed File using FTP or to instruct given channel authority to download the Feed File over HTTP protocol.
Usually, channels provide two ways how to upload product data:
Note that for Feed File submission you need to have a merchant account with given channel authority. In Feed Preview click tab Submission Manual for further instructions on how to proceed with feed submission: