I would like to activate a comments section and be able to discuss with the team withing each user story. Is that possible?
There is discussion tab that can be used to added comments and discussion comments to a user story.
This link will provide you with more information.
A Rich Text Format field for the description of your user story. Capture a brief description of your user story here. Enter any text in the description that will help all team members clearly understand the intent of the user story.
Please let us know if you have any questions.
Some organizations use Notes for this, but I'd agree with Christian that the Discussion tab is the best place for comments regarding a user story or really any work item in Agile Central.