In the finalize step you can match the internal Channable fields with the fields required by the feed. Each channel has different requirements for their data feed, we already filled in these requirements for you.
In the finalize step of your optimization the mandatory fields are colored in blue. Mandatory fields are required by the channel to be included in the export feed. When you hover over the question mark icon you can see possible values for these fields.
Recommended fields are orange. These fields can be added to the feed export to improve your listing but are not necessary.
Optional fields are colored gray, these fields can be included in the feed but are not necessary.
NOTE: Each export channel requires different information from your feed, thus each feed has different mandatory fields.