This tab displays all collaborations for which you sent a 'Completion request' to the brand.
At this stage you presumably completed all the work and are waiting for the brand to review your links and close the collaboration.
If not, the brand might communicate with you in the Messages section and request some tasks to be completed and in that case, update them with a message as soon as you do that and submit the relevant link as proof.
Once the brand decides to complete and close the collaboration, they will be able to review your performance via a 5-star rating system and an optional comment box.
On the top right of your collaboration area, there's always a collaboration status update (deadline's days left, confirmations, agreement sent, waiting on a reply, ...).
Be sure to check it out for extra information on the status of the collaboration.