To interact with Trade Me, Tradevine needs to be authorised with Trade Me. First you will need a login (account) for Trade Me, which you should already have set up especially if you are on either a My Products plan or a trial. Some plans allow for free additional Trade Me accounts. You cannot add additonal Trade Me channels if you are on a trial or Lite plan.
You can add additional Trade Me accounts via the Settings > Trade Me Settings screen.