Once all 'steps' (each being another tab or sub tab in the channel menu) are completed, only one action remain to actually start the syncronisation with the channel.
To do so navigate to the tab labeled 'Activation'. There you will see an overview of all the configured settings, filters, rules and mappings that are required and or relevant for this channel. The amount of listed options and required settings listed on this page, may therefore vary depending on the channel.
If required settings such as API keys or authorisation tokens have been left empty (or if there is no product filter for example), you can not active a channel. This is an purpose, because there is no point activating tasks without proper authorisation or content. This will only result in failing API-calls or empty exports, which in turn will create wrong expectations. Therefore it is imperative that you configure all the required settings and mappings before activating a channel.
You can activate the synchronisation for a channel by pressing the slider on the right hand side.